Unfounded and Incorrect Charges

FNB has been consistenly charging me for unpaid items. The one I am disputing now is the fourth or fifth I am experiencing. I have once again been charged for an unpaid item which allegedly happened on the 22nd of April. The 22nd of April was my pay day. There was money in my account, thereforet there was no unpaid item to charge for. I explained to the last consultant I spoke to that whenever I make purchases my app reflects that there is an available balance. Yet I keep getting charged for unpaid items. If the app and the website reflect a positive balance when I decide to make purchases - which are ALWAYS within the stipulated available amount - then they are representing incorrect information and the fault lies with them. Furthermore my in contact messages always report the amount of money spent, as well as the available balance after each transaction. If this in contact information is not accurate, I should not have to suffer for it. I want the charge for the unpaid item on the 22nd of April to be reversed, and I would appreciate it if FNB stops taking my money with no cause.