Negative balance charged via debit card & deducted from proceeds

We have an issue with our disbursments where 2 payment periods were in a negative balance and that balance was charged via debit card and paid to Amazon.

The negative balance was then also carried forward to the next period and deducted from proceeds in that period, despite already being paid in full.

I've been trying to resolve this with seller support since 9th Jan, but they just keep sending me copy/pasted scripts on how disbursments work and where i can find the information in seller central - they don't appear to be listening or understanding the issue.

Has anybody had the same problem? How was it resolved?