Vodacom *****ing from the dead

My father passed away in January 2020, at the time he had 2 vodacom contacts that was due to end during the course of 2020 so my mother, who is a pensioner, kept paying the account but when the time came for the contract to end vodacom kept debiting the account to this day, my mother has visited vodacom on many occasions to try and close the account but vodacom will not allow this, surely if a 24 month contract come to an end it should stop automatically???