No authority to debit cause i have been paying cash

I'm very disappointed with the service received at fnb, parktown. I recently changed my acc to Fnb now i got my salary and I tried to withdraw but I'm told money has been reserved for home loan, my bond is 3.7k y reserve 5.4 leaving me with no money to go home. The consultant told me they need proof dat I paid cause i normally eft to fnb homeloan but not my statement. Which i dont understand. I need Fnb home loan to tell me who authorise them to debit my acc, and y not call me and make an arrangement if my bond is in arrears. Is Fnb taking advantage of clients or what? I hate fnb for thinking they can do as they please with the money we work so hard for.