diff --git a/app/jobs/complete_backorder_job.rb b/app/jobs/complete_backorder_job.rb
index db177c5cf5..8737996a6e 100644
--- a/app/jobs/complete_backorder_job.rb
+++ b/app/jobs/complete_backorder_job.rb
@@ -24,8 +24,7 @@ class CompleteBackorderJob < ApplicationJob
 
     urls = FdcUrlBuilder.new(order.lines[0].offer.offeredItem.semanticId)
 
-    variants = order_cycle.variants_distributed_by(distributor)
-    adjust_quantities(order_cycle, user, order, urls, variants)
+    BackorderUpdater.new.update(order, user, distributor, order_cycle)
 
     FdcBackorderer.new(user, urls).complete_order(order)
 
@@ -36,55 +35,4 @@ class CompleteBackorderJob < ApplicationJob
 
     raise
   end
-
-  # Check if we have enough stock to reduce the backorder.
-  #
-  # Our local stock can increase when users cancel their orders.
-  # But stock levels could also have been adjusted manually. So we review all
-  # quantities before finalising the order.
-  def adjust_quantities(order_cycle, user, order, urls, variants)
-    broker = FdcOfferBroker.new(user, urls)
-
-    order.lines.each do |line|
-      line.quantity = line.quantity.to_i
-      wholesale_product_id = line.offer.offeredItem.semanticId
-      transformation = broker.wholesale_to_retail(wholesale_product_id)
-      linked_variant = variants.linked_to(transformation.retail_product_id)
-
-      # Assumption: If a transformation is present then we only sell the retail
-      # variant. If that can't be found, it was deleted and we'll ignore that
-      # for now.
-      next if linked_variant.nil?
-
-      # Find all line items for this order cycle
-      # Update quantity accordingly
-      if linked_variant.on_demand
-        release_superfluous_stock(line, linked_variant, transformation)
-      else
-        aggregate_final_quantities(order_cycle, line, linked_variant, transformation)
-      end
-    end
-
-    # Clean up empty lines:
-    order.lines.reject! { |line| line.quantity.zero? }
-  end
-
-  def release_superfluous_stock(line, linked_variant, transformation)
-    # Note that a division of integers dismisses the remainder, like `floor`:
-    wholesale_items_contained_in_stock = linked_variant.on_hand / transformation.factor
-
-    # But maybe we didn't actually order that much:
-    deductable_quantity = [line.quantity, wholesale_items_contained_in_stock].min
-    line.quantity -= deductable_quantity
-
-    retail_stock_changes = deductable_quantity * transformation.factor
-    linked_variant.on_hand -= retail_stock_changes
-  end
-
-  def aggregate_final_quantities(order_cycle, line, variant, transformation)
-    orders = order_cycle.orders.invoiceable
-    quantity = Spree::LineItem.where(order: orders, variant:).sum(:quantity)
-    wholesale_quantity = (quantity.to_f / transformation.factor).ceil
-    line.quantity = wholesale_quantity
-  end
 end
diff --git a/app/services/backorder_updater.rb b/app/services/backorder_updater.rb
index d8425a3ea7..ad84cec505 100644
--- a/app/services/backorder_updater.rb
+++ b/app/services/backorder_updater.rb
@@ -8,7 +8,9 @@ class BackorderUpdater
   # Given an OFN order was created, changed or cancelled,
   # we re-calculate how much to order in for every variant.
   def amend_backorder(order)
-    variants = distributed_linked_variants(order)
+    order_cycle = order.order_cycle
+    distributor = order.distributor
+    variants = distributed_linked_variants(order_cycle, distributor)
 
     # Temporary code: once we don't need a variant link to look up the
     # backorder, we don't need this check anymore.
@@ -17,8 +19,21 @@ class BackorderUpdater
     # cycle before and got ordered before being removed from the order cycle.
     return unless variants.any?
 
+    # We are assuming that all variants are linked to the same wholesale
+    # shop and its catalog:
+    reference_link = variants[0].semantic_links[0].semantic_id
     user = order.distributor.owner
-    order_cycle = order.order_cycle
+    urls = FdcUrlBuilder.new(reference_link)
+    orderer = FdcBackorderer.new(user, urls)
+
+    backorder = orderer.find_open_order(order)
+
+    update(backorder, user, distributor, order_cycle)
+  end
+
+  # Update a given backorder according to a distributor's order cycle.
+  def update(backorder, user, distributor, order_cycle)
+    variants = distributed_linked_variants(order_cycle, distributor)
 
     # We are assuming that all variants are linked to the same wholesale
     # shop and its catalog:
@@ -27,11 +42,10 @@ class BackorderUpdater
     orderer = FdcBackorderer.new(user, urls)
     broker = FdcOfferBroker.new(user, urls)
 
-    backorder = orderer.find_open_order(order)
-
     updated_lines = update_order_lines(backorder, order_cycle, variants, broker, orderer)
     unprocessed_lines = backorder.lines.to_set - updated_lines
-    cancel_stale_lines(unprocessed_lines, order, broker)
+    managed_variants = managed_linked_variants(user, order_cycle, distributor)
+    cancel_stale_lines(unprocessed_lines, managed_variants, broker)
 
     # Clean up empty lines:
     backorder.lines.reject! { |line| line.quantity.zero? }
@@ -54,8 +68,7 @@ class BackorderUpdater
     end
   end
 
-  def cancel_stale_lines(unprocessed_lines, order, broker)
-    managed_variants = managed_linked_variants(order)
+  def cancel_stale_lines(unprocessed_lines, managed_variants, broker)
     unprocessed_lines.each do |line|
       wholesale_quantity = line.quantity.to_i
       wholesale_product_id = line.offer.offeredItem.semanticId
@@ -79,6 +92,8 @@ class BackorderUpdater
   end
 
   def adjust_stock(variant, solution, line)
+    line.quantity = line.quantity.to_i
+
     if variant.on_hand.negative?
       needed_quantity = -1 * variant.on_hand # We need to replenish it.
 
@@ -92,7 +107,7 @@ class BackorderUpdater
       # and we'll account for that in our stock levels.
       retail_quantity = wholesale_quantity * solution.factor
 
-      line.quantity = line.quantity.to_i + wholesale_quantity
+      line.quantity += wholesale_quantity
       variant.on_hand += retail_quantity
     else
       # Note that a division of integers dismisses the remainder, like `floor`:
@@ -110,18 +125,15 @@ class BackorderUpdater
     end
   end
 
-  def managed_linked_variants(order)
-    user = order.distributor.owner
-    order_cycle = order.order_cycle
-
+  def managed_linked_variants(user, order_cycle, distributor)
     # These permissions may be too complex. Here may be scope to optimise.
     permissions = OpenFoodNetwork::OrderCyclePermissions.new(user, order_cycle)
-    permissions.visible_variants_for_outgoing_exchanges_to(order.distributor)
+    permissions.visible_variants_for_outgoing_exchanges_to(distributor)
       .where.associated(:semantic_links)
   end
 
-  def distributed_linked_variants(order)
-    order.order_cycle.variants_distributed_by(order.distributor)
+  def distributed_linked_variants(order_cycle, distributor)
+    order_cycle.variants_distributed_by(distributor)
       .where.associated(:semantic_links)
   end
 
diff --git a/spec/services/backorder_updater_spec.rb b/spec/services/backorder_updater_spec.rb
index da5e4aa6d2..48aa125fdc 100644
--- a/spec/services/backorder_updater_spec.rb
+++ b/spec/services/backorder_updater_spec.rb
@@ -110,8 +110,10 @@ RSpec.describe BackorderUpdater do
   end
 
   describe "#distributed_linked_variants" do
+    let(:order_cycle) { order.order_cycle }
+
     it "selects available variants with semantic links" do
-      variants = subject.distributed_linked_variants(order)
+      variants = subject.distributed_linked_variants(order_cycle, distributor)
       expect(variants).to match_array [beans, chia_seed]
     end
   end