The biggest financial *******

On the 4th August , I made an in store purchase with my card, the transaction was approved, I even got an sms notification stating how much was deducted and how much was left in my account. The next day I made a purchase at wimpy, the transaction went through, I got the sms with transaction details and balance available. On the 10th I check my statement online and see that I have been charged R150 bank charges. I called the customer care and they said it was for the transaction done on the 4th. This is ****************, how can I be charged for a transaction that went through. The money was already reserved for the merchant, and also I continued to use my card after that and the transactions went through. FNB you are *****ing from your customers. I do not even feel that I can use my card anymore because I am scared of mysterious bank charges that are going to appear from nowhere. I have never been into a shop where I had insufficient funds and the transaction is approved. it is always declined. Which whatever that bogus charge is for, I cannot protect myself against it as there is no way of knowing how and when it is determined. Please can someone contact me with regards to closing all my accounts with you and think its time for me to look for a more trustworthy bank.