Breach of contract

I have contract with MTN for 2 devices,according to my contract I signed it stipulated that I will be paying using debit order method,debit order must run on the 15th ,today is the 20th.MTN decided not deduct my account.I tried to call them on the 17th of January,I was told that they will do so on the following day.I tried to email they,their email not going through.today I spoke to one of their consultant and the answers she is giving me is like she is not even sure.MTN want to ruin my credit health.