Been over charged on contract

I reported to mtn about being overcharged on my account (for over a year) at the end of last year. They requested that I provide proof of me being overcharged. After eventually tracking down my original contract. MTN has agreed to re-imburse me for the extra charges and the double connection fee charge. After numerous back and forth emails, I still havent been re-imbursed. <br> Their response: \Journals are bank dependant once done by MTN