What a *******

Every month I have to contact FNB regarding my accounts always being on a negative due to "pending transactions" and merchants banking days after purchases. Explanations I get always is "you always have to have sufficient amount of money in your available balance to accommodate the pending transaction". Yet when I buy I pay for those goods and the money I used to purchase is already paid and moved out of my Available balance and kept in "balance" as reserved. So basically I have to have the double the amount for what I purchase so that it can accommodate whatever pending transactions I have in my account