FNB Pending Isuues

The Bank encourages its customers to use their cards for purchase but at the same time their customers are inconvenienced by payments that dont go through immediately. the customer receives an sms after purchase that money has been reserved, after few days the same amount is deducted from your account. if money is reserved, why do we get deductions of the same item that was reserved? as a customer i feel cheated on because one cannot monitor properly.

this issue needs to be resolved by the bank or im switching banks.