Card division lack interest to repayment plans

I requested my credit card to be put on a repayment only plan about 6 months ago. The amount I advised I would pay covered the monthly interest plus some of the capital amount. The minimum payment made monthly was either the minimum offered amount or more without missing a payment. I stopped getting statements on the account and it was taken off my profile so I couldnt keep track of the account payments. After begging until I was blue in the face, and lodging a complaint, I eventually received a statement. (complaint reference ***). Upon receiving the statement, interest to the extent of +-40 percent is charged some months, causing the balance to escalate above the original amount, meaning that the debt will never be repaid. I have queried this on numerous occasions, but have yet to receive any response, interest or explanation from Card division. (emails are ignored) Please could I have a response from card division as I cannot see how interest can be charged at 40%. Please could these excessive charges/interest be reversed in order for the balance to come down as arranged and that monthly statements are sent.