Thank for ruining my life

I received a phone call from a guy by the name of Enrico calling on behalf of mtn. he told me that mtn wanted to reward me for being a great customer and they are giving a free tablet. now all I have to pay for is the 1gb of data,25 sms' s and R100 airtime. and all that he said will be for under R200 (repayment). now this tablet was delivered and within 24 hours I called to cancel the contract and I was told that someone will get back to me. a few days ago I received an sms saying I must pay a thousand something to cancel of which Enrico told me that if I cancelled within 24/48 hours I would only be liable for a months subscription. now I am stuck with a contact I don't want. last night my account was debited crose to R400 for tjis contact that was supposed to be worth less than R200. apparently I have 2 sim cards that are worth that much of which I wasn't informed of and I have 1 sim card. All I asked of mtn is to cancel this contract so I can continue with my life without any stress. I have not been helped. I phoned them more than 3 times begging to be helped.<br> Please help me get out of this contract.