MTN debited client with R54000, on a contract for R529 per month.

My client renewed his contract with MTN on 8 November 2020 and has had his phone disconnected for over a month now as they want him to pay over R54000,00. He is 78 years old and does not download anything except whats ap. Several letters have been written with no assistance. The number in question is ***, and the contract was entered into at the Nelspruit Branch. Please be very careful when dealing with MTN as they will not take much interest in you when you have a problem