Debit Ted twice for a cancelled contracts

Mtn has been debiting me for two months now and they taking time to credit my account we are approaching the second month I have been waiting for my refund they not doing it and I need to pay my contract phone while they owe me more than I need to pay them and when I don't pay my phone it's gonna lead me to areas! I have been speaking to them calling sending emails from the first of August till now