MTN Exorbitant amounts

Mtn is the worst. I had a contract of R339, but amounts ranging between R359 and R370 were taken every month from my account. When I enquire,they just say I should email,but nothing gets done. Mind you,I was charged almost R3000 the first month. Now my contract is completed,they are overcharging as usual. Now they say I owe over R700,even though I cancelled my contract. I would not encourage anyone to deal with MTN,they are the worst bunch