Nedbank messing up your financial life difficult

I have a personal loan with nedbank and I made arrangements to pay my arrears with Ashly Abrahams second week of February. Come end of the month they double debited my account. I called them back and I was told that the arrangement they made is not valid though it was valid when they called after taking all my money it was invalid. I kept on calling and I spoke to Mashudu Musandia and she said Her manager will give me a call that was on the 4th of march. Can anybody assist.