Pathetic service once again at Fnb

After 2 years of being unemployed, I decided to re-open my Fnb acc, to my dismay and utmost regret a big amount was taken out of my account. I queried it with the bank and they then said that I owed the bank that amount for a loan that I had taken 5 years ago. On my transunion report it clearly shows that this loan is now closed bcos it is a prescribed debt, the fact that Fnb went into my acc without my permission or arrangement made by me and subsequently took away this money is utter nonsense and unprofessional. I regret ever opening this account.