No response on any enquiries but deduct money for no services (Vodacom provider)

A consultant phoned my elderly mother on her birthday, to tell her what for her birthday she will receive a cellphone. She declined and told them she is not interested, the man just kept on talking, she refused to confirm or give her id, and the call was ended. A few days later she received a parcel, 2 cellphones. Since June we are trying to return the phones with no success, the one time they did answer at the call centre, they promised to contact me to arrange a pick up for the phones...till today I cant get hold of them or received any emails, calls. They deducted money from her account through Vodacom to the amount of R950.00 and this month again R451.00. We stop the 1st payment, Vodacom blocked my mothers phone. She is old and if the phone is block she cannot contact anyone, so we had to pay. Vodacom is also no assistance, they just say we need to contact Afrizone. Can anybody please advise? My mum is a pensioner and cant afford the extra bill.