MTN overcharged contract

MTN is the worst network provider. The worst customer service in the contract side. I have been overcharged since February My bill was supposed to go down by R718,40 after a downgrade and insurance cancellation. I have been overcharged by R718,40 since February. I have called a number of times and each person I speak to tells me a new story. This is not the first time MTN proves to be the worst service provider. I had the worst experience last year when I was doing an upgrade and now they keep on getting worse.