Are MTN *******?

I signed a new contract at MTN in April 2018. Contract reflects correct package and price as well as all emails and correspondence to and from the local branch. However they are deducting more every month and charging for a package that I didn't sign for. While I am receiving the extra data, sms's and airtime, I didn't ask for this. They will not credit me as we are using the data etc which I can understand. However how long does it take to rectify the amount on my billing as 3 months later I am still querying it and still overpaying. This should be ******* and I should be able to cancel my contract and go elsewhere. Every month the local branch promise me that it has been sorted out and every month I get billed for a package that I didn't ask for. I have re**** on the local branch where I signed the contract to sort it out as trying to phone MTN is impossible. You can hold on for an hour or more and then they are useless when you finally get through. Please help me.