Super bad service from mtn

I have spoken to mtn more than once about them debit order my account on the 26th of every month and some how they promise me that it can be done and has been done on my account and now after speaking to them about this situation and informing them that I have other responsibilities they keep on taking off there money on end of the month, now they have suspended my account for outgoing and want me to settle my account now after I told them I don't have money now and only get paid on the 26th of this month