Overcharged

I have opened up a new contract with MTN (and it was approved on the 5th July 2015) upon openg the contract, I requested that I would like a Top-Up closed line, all detaills to remain the same as the current one that I have with them, however, the limit was not set and the bill run up I was debited to R2309.0 on the 21st July 2025 which was INCORRECT especially when I've requested a Top-Up closed line. This month I've been debited with R544 and it clearly states R499.00 in their catelgoue, so the question is, WHERE do these additional costs come from? <br> <br> They also do not answer their phones/it just rings. Queries have been logged but nobody has go back to me with ANY sort of feedback.