Poor service or assistance from upgrade company CCI regarding MTN contract

My aged mother(89 years)has been contacted to upgrade her MTN contract.She was issued with a handset that she did not want because she actually wanted to downgrade.I assisted her to return the handset at MTN Brooklyn Pretoria and contacted CCI to cancel this upgrade in October 2019.Since then we are battling to get this contract cancelled and have been very rudely treated.Even MTN cannot get any assistance from this company who is actually in their service.I do hope that this matter can be finalised as soon as possible as this is a very frustrating situation.