Bill for contract

I took out a contract last year for my house . The amount I am meant to pay on this is R399 every month . Now in Jan of 2017 my contract changed without my consent they added a extra R99 , I didn't realize I was paying that much . It was when I asked a call center agent to check for me how long this has been going on for that he informed me that it started in January. Now sometime last week I called the call center asking for the recording of the conversation that says I asked for an extra R99 on my contract. Still waiting up til now . I want a refund for all the months that I have been paying for this . I will take the matter further if I do not get my refund .