Don't seem to like frequent flyers
I fly quite a bit, but have given up booking BA through Quidco. Most transactions track, but are then declined at a later date. I have carefully followed the rules (and there is nothing about having to be a new customer), and Quidco tracked transactions with other retailers work, so I can only assume it is something related to my booking activity with them. I just wish I could offer better advice to guarantee success for your cashback.