Secretly deducting money from my account

Dear FNB Maybe no so 'dear' this time. Explain to me the purpose of your charges on my account. On the 16th last month you charged R200. When I just asked I was told it's purchases that were done at Pick 'n pay and Spar. According to you there was no funds when I did these purchases. This is the first: All along when I busy something funds will be reserved for a particular Merchant then later the amount will go off my account completely. But until then, the amount/s will still reflect on my account until they are released to the merchant. I have never in the past purchased sometsomething using my card,, and the same amount still showed as available on my account still. The balance will still reflect but not available. I do not understand your latest practice. I was told the merchant delayed to send the claim. This does not affect me as you have already reserved the funds for that merchant. In August you did the same thing. I used my card to pay tall gate. In this case there were enough funds still available. You decided not to reservethe funds. When the claim came from Sanral you paid but then charge me for 'no funds item'. Why? There was money when the request for purchase was done. Explain to me. I'm just a lay man who happen to notice when something is wrong. I might not know the complexity I your system but I think it is doing something wrong. Or is it the case I heard on the radio where FNB is secretly taking money from clients to make up for their loss.