I am having the same issue.
When claiming my reward card, I select my latest account number, then it goes to a blank screen with only BT header and footer.
Welcome to the BT Community and thanks for your post! I have moved your post to start your own thread as the thread you posted on has already been marked as solved.
I am sorry for the problems you're having claiming for your reward card. I have sent you a private message with instructions on how you can send us over your details and we'll look into this for you. See: Private messages
I had an email to say I can claim my reward card, yet I am still having the same problem.
I have sent my details over as requested.