Bad service and lack of urgency for my dispute. Two weeks waiting.

Two weeks ago a company called Thrifty car rental send me email after a year that I had an accident and I had a super cover with access of 3500, which I payed partly with my deposit and another R2000 was taken last year. I didn't hear from this company again two weeks ago I got an email from them claiming that I was owing them R29980 and the email said if I don't respond they will take the funds from my account and I did respond and I went as far as calling them no avail. The R29980 was taken from my account and the bank approved that without me having an overdraft. My account is sitting on minize and it's been two weeks. I went to the banker and she made me to sign a form. After a week she called me again that the form I signed was incorrect. I had to go again to sign another form. I have been with FNB for many years and I have 6 accounts with the same bank that is disappointing me and worked against me. I have been struggling to get assistance. My account is on minize and that is affecting my credit. FNB have failed me and I lost hope and trust to the bank I put all my eggs into. Dispute is taking forever and no one is prioritizing this and I. Frustrated and annoyed.