MTN sales agent ******* my mom into taking a second contract

I would like to report a MTN call centre agent that **** to my mom and told her that she can get a router on the same contract that she has and she will pay less than what she is paying only to find out that she ******* her there's no such thing. My mother is now paying for 2 contracts that she can not afford and at an MTN store they told her that there's nothing they can do the lady **** to her. Why can't they trace her since their calls are recorded and cancel the contract because my mom can't afford to pay for that second contract. Please help my mom cancel the second contract my no is *** thanks