I have tested it again,and it does allows the user to place order without balance although what happened before was that the single transaction some customers placed will duplicate and therefore making the other duplication as debt in their wallet, the original transactions will be debited from their WALLet while the duplicate will retain their wallet balance as debt because they are owning the system since they did not have funds for the duplication, this error has happened like 5 times on my website and it was after I installed your plugin.

Also, when u are doing the update, make sure that the user can be notified too when withdrawal request has been sent and completed