Std Bank Home loans *****ing us over again!!

Yesterday we received an unfortunate surprise - our bond instalment jumped by almost R400. When calling in today I was told that the instalment is correct, and it was a system readjustment to bring all bonds in line with outstanding balances. Really - how the f@#k does Std Bank Home loans make a mistake like this years back and just increase the instalment suddenly without any notification? Not an email or letter of apology/explanation....nothing!! We've been paying a set instalment for years and as you can imagine have budgets to work around. To suddenly have to pay extra for another mess up by Standard Bank home loans, is not acceptable. I would ask that our instalment goes back to what it was for the time being to give us time, but having dealt with Std Bank Home Loans too many times in the past, I know they don't care.