Charge for benefits that I have not requested

I paid my account on the 20th of March the whole amount I was owing them, they are calling me stating I owe them the benefits amount of R55 that I have not requested. I am not prepare to pay this amount because they are robbing people and they are not aware. I want them to refund the they have debited me from the day of inception to day and stop calling about this amount I have not requested