MTN not happy

My mother cancelled her contract 5 years ago. July they took off a payment via debt order and again in August. We got hold of MTN and was told that the contract had been renewed on a month to month basis, BUT MY MOTHER HAD NOT SIGNED OR CONFIRMED THIS AGREEMENT. When we asked who gave the authorisation for this they couldn't give an answer. My mother is a pensioner that is why she cancelled this contract 5 years ago. We are wanting answers and wanting this to be stopped/cancelled. PLEASE THIS IS NOT RIGHT. WE WANT THIS SORTED OUT.