FNB robs my account every now n then!

I am really disappointed with FNB I purchased good on worth about 300 and the amount was deducted in my account my account was on a minus but it already reflected my account balance decreased then again in a few days my account suddenly changes from minus 287 to 443 then again suddenly they deducted 240 from my account. Over the past few months I have noticed my account money I am deducted money when I purchase and again says pending then after a few days they deduct again . I really don’t understand this time I saw real proof that they deduct my account twice. Hello peter pls investigate on this matter since it’s been on going. I am about close all my account with FNB and remove my investments. They even claim that to honor goods which they had not cleared and charged twice is 120 ???????? they charged me 240 for honoring goods worth 287 . When they had already deducted and charged about 59 on top