Unfair charges

I have been charged 420 of item paid fee. When I swipe I have money in my account but fnb will charge me and still insist that they paid for my item how? I am not overdrawn because of insufficient funds to pay for my item but I am in acess because of their unfair charges. Can I have this fees reversed please . I am struggling with my finances as it is I cannot afford to be ****med by my own bank.i would also appreciates for them to show me on my TRNH how they condoned my payment because if so I was supposed to be overdrawn. No maan.