cancelled contract

Once again mtn has taken money out of my account after my contract being cancelled and put to pay as you go. Due to tge fact that i do not live in south africa and my sa accou t does not get used there is no money in that account. So when mtn takes money i have to pay a R140 everytime the charge gets refused. I expect this money to be paid by mtn as this is the 4th complaint i have put against mtn due to their incompetance and un able to keep up with their customers. If this money is not paid i will be taking this up with the police. As what mtn is doing is *******.