Standard bank its my right to settle my account, when i want to...

Okay so i have a personal loan with standard bank, i want to pay up my loan, and ive never been so frustrated, they keep returning the money back to my account and saying an error occurred, i honestly dont understand why we must struggle so much to pay off a loan, i cant help but feel that this done deliberately, number one why cant i manage my personal loan on my app or online, just like any other bank, surely i should be able to pay my lian anytine i feel like, firstly to get a settlement letter you have to call and hold the line for almost a hour, before you can get anyhelp, secondly why is not listed on e registered companies, ive been trying to pay up this loan for 2days now, as per settlement letter given, its funny how when they give you the loan they are so quick efficient, but when you choose to settle it, i have to go through so much trouble, so not on standard bank, day 3, im still stuck with money in my account keep trying to transfer, money keeps getting returned..