While most of the time, the inventory control worked flawlessly, we've been experiencing ever more problems in the last few months, especially with a specific type of payment used, where an order is not finalized until the actual payment is done, that is , a customer is required to return to the webshop after payment.
For Paypal I get two email notifications:
1. order has been placed
2. order is in process and paid for.
No issues here
Neither are there issues for off-line payments by bank transfer
1. order has been placed
2. payment instructions for off-line bank transfer
However, for online payments towards iDEAL (bancontact or SoFort) I get two identical notifications!
This has been going on for the past 4-5 months already, which coincides with the ever increasing problem of DOUBLE inventory DECREASES where twice the amount of ordered items are subtracted from the inventory.
As I also get inventory warnings for low stock, I see this most clearly when e.g. a product has 4 items left and I get a 'low inventory' warning , there are 0 items left and then upon checking , a customer just ordered 2 !
Most of the time, when I check, the inventory will have jumped back from 0 to 2.
But sometimes, it stays on 0 .. or does the reverse and, even though a customer paid for 2 items, NO subtractions took place and inventory stays on 4!
I looked at the suggested order statuses in the demo shop and saw only one difference : backordered items, where the demo is set on 'increase'.
As we allow customers to order out of stock items (for a higher price, to accommodate extra shipping costs) we used the backorder status for delayed or partial shipments.
Thinking this could be the problem, I made another status for that kind of order, so the 'backorder' status is back on 'increase' (like cancelled, declined or failed orders).
I can't believe it is the problem as, like I wrote, Paypal or off-line bank transfer payments never gave rise to problems.
What can have gone wrong ? It sucks the joy out of me having to constantly check whether the shop inventory matches the actual inventory (which I also keep track of in a spreadsheet).
Edit: the problem seems to arise mostly when a customer changes his/her mind and backtracks to the shop in order to add/subtract an item to the cart or wants to apply reward points or erroneously chose the wrong payment method (iDEAL is the first and main payment in our country and as such is chosen by default)
Thanks for reading/listening
Yvana (partner of Anthony)