Unfair declined fees billed

How can you charge me R150 for a R64 declined transaction? Is this a logical thing? I swiped my card for this just short of a week ago and it was sitting in pending for the longest time.. Then suddenly out of nowhere it comes out of pending and then you bill be R150 for something that, when my account had funds in, there were sufficient funds available?

Surely FNB should reserve those funds until the vendor has collected it from the bank, now you are penalizing me, but when I swiped my cards the funds were available?

how unfair is this?