I had the same issue with the site stating I wasn't eligible. I just raised an online complaint with BT and they have apologised and promised to send me out my Reward Card. I was then happy for BT to close down the complaint there and then. I made a copy of the online conversation.
Hi @MrShingALing Welcome to the forum and thanks for posting that when you raised your complaint online it was resolved so quickly. I'm sure that you will receive the Reward Card. If you have any issues after the timescale advised just drop us a post back.