Bad service

I keep having the same problem, when i need to pay bond for my parents. i have been paying my parent home loan for over 5 year. but when i need to change banking details i must run around and its irritating. I was asked to call the call center they will help. when i do, the call center says i must visit the branch. When im at the branch they give me a phone to speak to the call center. All i want is to change banking details so i can continue paying that home loan. its accumulating arrears. can someone who cares help me