Bad Debt write-offs are usually done thru Acct Rec module. Go into customer sales and enter the customer name, for invoice nbr use the AJE nbr or something like MMMYY-W/O and use same date as the YE adjustment. Enter the bad debt as a negative taxable amount using GL 5620 - this should show both the Bad Debt amount and GST Collected amount. This will clear this from the customer account and credit the Account Receivable.

I'm just not sure why GL 1201 is only 2000 and 1205 is 10000. You should ask your accountant to explain that to you.