Won't refund

In December MTN attempted to debit my account but found no funds, so I contacted them, got their banking details and references . I then paid them via eft and emailed the proof of payment even got confirmation of receipt. Around the 15th I received an email informing me that my account would be debited twice.<br> <br> I called MTN again and sent through proof again, and confirmed receipt. On the 25th my account was debited twice still. I called them again, emailed the proof again and. Was informed that I will be refunded within 48hours.<br> <br> 48hours later I was informed that the money will not be refunded to my account but will go towards February's instalment and there was nothing that could be done!<br> <br> I need MTN to refund me as it is not part of my contract.