Due to current DEAR Inventory limitation every sale task can have only one credit note. If client returns items second time on the same sale order system can't allocate second credit note to the same sale task. User will have to process this refund manually. There are two actions involved:
Reduce accounts payable/sale amount and
Restock returned item and
To reduce accounts payable/sale amount
1. Go to Sale -> New Sale (Services Only) and create a new invoice with the amount you wish to credit and 100% discount so you end up with 0 due.
2. Create a Credit note for this invoice. This time you will use 0% discount.
To restock returned item use stock adjustments module.
Go to Inventory->New Stock Adjustment, add item under 'Zero stock on hand' section
Mark entry in the sale channel's Log tab as Processed.
Return to sales channel Log tab, find not processed entry and mark this entry as processed.