Some customers report that their stock levels are reducing to less than 0, or a negative value.
The cause is generated by either of the following:
1) Advanced orders being enabled - Advanced orders allow stock to reduce to less to zero.
2) Bank or gateway communication error - When an order is placed and payment is made through a real-time credit card option, our shopping cart waits for a signal to return from the bank to let the cart know if payment is approved or declined.
E.g. During the processing of a transaction, if the bank is busy and doesn't send this signal, the cart must decline the order after a short while. In this case, a customer will go back a page and attempt to purchase again, this time the order is approved.
Since the first order attempt is declined, no stock is reduced. On the second successful attempt, the stock is reduced to 0.
10mins later the bank sends a signal saying payment for first order was approved so it updates that order ID to approved and then stock is reduced to -1.
Some banks are better than others with communication or charging que's. We're happy to discuss your options if you would like to email or call a representative today.