Cancellation of an existing contract

I purchased a cellphone from MTN 2018 march and phoned in today spoke to Stembiso to do a cancelation due to me not being interested in an upgrade. Stembiso advised cancelation department is not available to assist however I will still be liable to pay R259 for munites in the month of April and the promo "handset" will cancel advised I dont need a carry over and needs the contract to be cancelled after this months billing. MTN did thus same thing to me a few years ago and handed me over to MDB, that specific contract run for 30 months and I had to pay legal cost of + and had to clear my name from ITC. In terms of TCF this is unfair practise contracts run for a term and thereafter it cancels.

Kindly look into ut and revert back to me.