Bad service at MTN micky mouse

My contract ended with MTN and even went as far as going to MTN store at Benoni to ensure that it was canceled in my presence. I have asked for a letter from the store and nothing was provided to me. They informed me that there was nothing to worry about. Now in the month of December they decided to make a another deduction and increased the amount. Now their excuse will be that I will have to wait for the money to be paid back to me but never stopped as it should have. This will be the second time that this scenario will taking place in less than a year. MTN micky mouse business