MTN contract expired - but they are still deducting

My mother took out a Laptop+Data contract at MTN Cape Gate two years ago. The Contract came to an end in March 2021.

MTN is still deducting money from my mother's account. We went in store to ensure the contract is canceled three times. But MTN is still deducting money after they promised that the contract will be canceled.

I request assistance in terms of an explanation and progress of the cancelation, as going to an MTN store is a waste of time - and unforseen deductions are made which is unacceptable.