Refusal to change my instalment increase date even after I have it in writing and had inform them telephonically,insisting on increasing my instalment everymonth even before my salary increase.

I`m so disappointed because this is causing me unnecessary arrears in my account. They just sent me a statement to say even next year there are going to do the same thing,(and this is not according to our contract) after they have promised to look into it and get back to me but never did.