Unauthorized debit order

I have a debit order with onAir TV running on an agreed date, I received an email instructing me that they will deduct on an earlier date since it's December. I responded to them telling them stick to our agreement as I will not have been paid by then and that will cause my account to have an unpaid debit order which will mess up my account. On Friday they deducted and the debit order was unpaid, now I have a bad record with the bank and credit record.