INCORRECT INVOICE - CALL CENTRE CANNOT ASSIST

I dialed 135 to speak to a consultant regarding my recent invoice I asked why I was charged R50 more than my usual amount The consultant said that they would get back to me (4 days ago) and nothing has been done about it I was due for an upgrade but I cancelled my contract I called 1958 several times to request a cancellation and each consultant told me that it was too early and that I needed to call back a month before the contract was due to end. I did so, (call on 31/7/18) for a contract due to end (30/9/18) The consultant that I spoke to at 135 advised me that I was charged a different rate because my contract had expired and this was a new rate because it was no longer the promotional rate that I used to pay on this contract I asked her why I was charged a different rate when I had already put a cancellation on this contract and she told me that she would escalate the matter further and that someone would get back to me

I do not want to pay this new amount as I followed the procedure to cancel my account and it was done on time

I do not want an additional charge on my account Please rectify this matter immediately