FNB how can we ***** your money

Both my account and credit card have been debited 3 times for the same amount and no one from FNB can explain other than that it's due to their systems being confused as month fell on a weekend and Monday was a holiday. I've been on their chats and called a hundred times and no one seems to know what the reason is. The consultants are not very helpful. They either cut you off or palm you off to the next person when they don't have a response. Going to a branch also doesn't help as you're given a phone to call the same people who can't help you. I want my money back FNB. How difficult can it be