Breach in agreement

I refer to agreement under reference ***, whereby I had an agreement to make payments on my loan account with FNB after going through some financial difficulties and advising them of the difficulties. I had agreed to pay R 823.51 plus an additional R 200 every month effective 1 October 2015 to bring my account up to date. But FNB collections department has debited me triple the R 823. 51 at the end of October and double the R 823. 51 at the end of September. I am now very frustrated as they never respond to my emails as they are avoiding written confirmation. Please can I get assistance with this. As per the NCR if I am under debt review I don't have to pay via a debt counsellor . I can make payment arrangement and pay the creditors directly. These guys fail to understand my situation.