MTN converted my number from Prepaid to Unisacontract without my permission

MTN have converted my number to a unisa contract without my permission, i am now not able to do simswap because MTN is not responding to an email i sent to MTN unisa orders email requesting a simswap. Unisa said we must get an mtn number to receive data not to get into a new contract. i went to mtn shop and did the sim swap it was successful and now my phone is blocked they are saying my sim swap was not successful. i am leaving this network with immediate effect i just want to keep my old Number