Debited money of cellphone contracts that ended

Bad experience with regards to the two cellphone contracts bought my Grandfather, the other one ended in 2023 and the other in 2024, but for the past 2 years Telkom has been debiting from my Grandfather 's standard bank account, we tried many times to cancel the contracts be it on different branches and I call them almost every week but we were told that the contract was cancelled only for them to debit again this month, when we call them they take us to square one. This is really affecting my Grandfather who is a pensioner, we therefore are in need of the refunds of the previous month because I believe my Grandfather 's rights were violated.