FNB card division, do you really need my money that desperately?

At exactly 09:08:41 on the 18/01, I made a purchase at Eastgate which went through my card. At exactly 09:09:48 the amount was refunded, that is 1minute and 7 seconds later, as it was an incorrect amount. As I stated the purchase went through my card immediately however when I contacted FNB an hour later to ask why the amount had not reflected as yet, they gave some asinine excuse about how the system will only allow the refund to go through 48 hours or more later. However if it did not reflect by Tuesday I should fill in a dispute form. How despicable. Does FNB really need my money that desperately that they will only refund it a few days later?