MTN refuse to refund money they owe

I recently immigrated from SA. I continued to pay my bill as my contract was nearly complete and I had arranged to have my account closed. MTN debited me (double) incorrectly for about 3 months prior, charging me R609.32 roughly and then refunding me the balance which was about half. My bank account was in the process of being closed, so a week or two before I was due to pay my last and final bill I requested that my mom went in and payed on my behalf as MTN would not be able to debit my account. She did so and was once again charged double.

It has now been three months of back and forth to try and have her refunded the balance. MTN are refusing to pay, giving excuses at every turn. If you don't pay them one Rand that you owe them, you are threatened, yet MTN can take as much time as they wish to pay a measly R231 back to someone.

This is a disgrace, I am HIGHLY irritated and I would like this matter to be dealt with immediately. My whole family back home are with MTN and on the next renewal I'm sure they will be re-thinking their provider. Please contact me via email as my phone is no longer in service - I can then furnish you with my mothers' details and you can rectify this.