Bad telesales service by MTN and solving this problem

My account has been suspended because of changing over to a new contract taken over the phone with a telesales person. My last one had 2 months left on the contract. There was no change to my devices and Sim cards just a changing the data needed and the talktime needed. Firstly my contract was in the black by almost the same amount as my normal monthly fee. So when I got my last bill I worked out what I needed to pay minus the admin fee and the advance prorater amount which was 3 times the amount of the new contract. I have sent this information to the powers that be however I haven't had the problem solved as there is no response. Not good service. Being an MTN customer for over 15 years this is how you keep your customers? MTN need to sort this out or this account will be cancelled.