Disappointing service from FNB!!

I am horrified at the service i have been receiving from FNB! My account is currently in excess as they continue to take money off my account, even though i have not used my account in over two weeks!! when i complain, they tell me its the merchants' problem, however, as far as i am concerned, FNB accounts have a "pending facility", which used to work. However, the last few months, no longer works. It will go to pending, i know it does, as i check. it then suddenly starts coming off my available balance as well. They will not help me at all. My account is constantly in excess because of this. i have spoken to their "so called" private bankers, who are rude and really are uninterested to assist. All i get is " you are liable" !