Mtn poor service

MTN claims that they had a technical issue wherein my debit order was reversed now they are debiting me twice this month and merely just saying sorry. All I know is I provided them with correct information even before first debit order, i did communicate with them regarding my information. I was told that everything is fine and I don't have any outstanding balances. This incident has affected my monthly budget and it is a huge inconvenience. What bothers me is that if I was somehow missing payments , I would be getting irritating calls and numerous warnings