Homeloan at Standard bank

I have a homeloan at Standard bank. I paid a big amount in advance during the years. I app**** for this amount in advance to be made available to me. Instead of doing that, my payment has been increased with R2000 which is being taken from my cheque account without my consent. My normal payment is being taken from my salary for the past 17 years. I get numerous answers when I contact the bank and every time a complain is lodged with no result at all. This are going on for 3 month now. I get SMS messages with reference numbers and when I phone the homeloan department the number is wrong. All I want at this stage is that my payment is being put back to the original amount and the payment from my cheque account being stopped.