Disgusted with FNB service

Fnb once again *****ed me over deducting a 1915 where my P.loan was paid up and they had to refund me for double debit but have been threatening me with lawyers that they will send a sherif while they have messed up I want my money back !! This is unacceptable and as a customer I am unsatisfied with this service . They claim to have called me but no call was made they sent me a statements letter to pay but I have paid them finished I hate this each time I have to put a review on and explain everything I also have been in an accident and can not go into the bank because I have PTSD they are totally inconsiderate