I find I get a lot of benefit from TopCashback and the BA/Avios e-stores but the lack of transparency when it comes to the reasons for cancelling or refusing transactions is extremely frustrating.
I understand that it is not worth investigating when you are due 20 Avios on a £20 Pizza Hut delivery order but these referral sites need to understand that when I have a £1,000 Hilton hotel booking refusing my 8,000 Avios without explanation is not on.