Exploitation of elderly customers

My mother, who is a pensioner, has been trying to cancel a contract from Vodacom, which was already fully paid by 1 July 2021. Every time she calls the cancellation/ customer care line, they try to negotiate new deals instead of listening to her - she only wants to convert the number to prepaid as she simply cannot afford to pay R700 per month for a two year old Huawei P30 Lite device! This is a nightmare, as none of the Vodacom stores can assist with this matter and the call centre agents do their best - after more than 30 minutes of negotiating every time - to exploit customers, especially the elderly.