wrong debit date

I took out a loan with Capitec about two years ago.I have never missed an installment but for some reason my personal cheque account get debited way before the actual debit date every single month.I have been to Festival Mall branch to advise them of such and requested them to rather change the date to the 26th or 27th they said they recquire a letter from my employer confirming that i get paid on the 26,but i dont get paid on the 26th and im not disputing the fact that I'm paid on the 25th,It is just that Capitec cannot honor their agreement that they will debit my account on the 25th,instead they debit on the 22,23 and even on the 15th,i did not sign for those dates.This has not only affected my bank account and the ridiculous bank charges which is R150 for each return.My credit record has also been affected,I have missed out on an opportunity to purchase my own house as my bank statement has been spoilt rotten by Capitec.I demand urgent intervention ,