mtn taking extra money.

My wife got a new data contract in december 2015. After the second month we realised they were charging us R309 instead of R249. We went to see an agent at MTN Key West shopping centre Krugersdorp end Feb 2016.The lady logged the querie and said she will phone my wife back within 48 hours. She never did. When my wife went in again the following week she was told on the system they are working on the querie and again will be phoned by one of them to let her know whats going on. Again no one phoned my wife. Now the 3rd month as arrived, and again the account shows R309. We went to MTN on 19 March and was told by the agent that there is no querie logged on the system and they are logging it from scratch again. If this is the type of service you get from a service provider they can be sure this will be the last time we take a contract with MTN.