Card Purchase Delay - Annoying !!!!

Whenever I make a debit card purchase using my Standard Bank cheque account there is 3 to 10 days delay before the payment goes off in my account. I do understand that there could be a merchant delay but it is unrealistic in my case because this happens to about 60% of the purchase I make per month. My husband also has a cheque account with standard bank and struggles with the same problem. We have also experience this problem for about the past six months.