Am confused.  Your response says to "When creating a Journal Entry (JE) to write off a vendor's negative balance (credit), simply debit the bank account and credit the default Accounts Payable (A/P) account instead. " 

There is no bank account, or cash, event happening.  I do not want to debit the bank account and then have a reconciliation nightmare as this is a non-cash event.  Could you please reword your solution and/or provide a different one where I am not debiting the bank account?