Late processing of funds

I am soo disappointed in fnb service, they debited me charges of R850 and today 300 which they say is their late unprossesed funds, I am seating here I don't have money for petrol. They said I will be refunded but instead they keep charging me for their mistakes. I WANT MY MONEY BACK Today, I will looked for different bank I am tired. Seivice is bad just give me my money.