i have the same issue. I was advised that I would receive an email 14 days after activation (4th March). This was for the £80.00 Mastercard. I have been able to register for the £40.00 M&S card, but then that is not through B.T
Unfortunately its not going to be possible at this time, for the forum moderators to investigate these promotions, as they are dealing with priority welfare escalations only.
All you can do is to ring BT, when the situation improves.
There are several people in the same situation. My dad included. It appears that many people who joined bt in February 2020 have not had their rewards card populated in their rewards area.
Currently waiting for a response from bt. I understand they are very busy in these difficult times. I do hope bt do the right thing and extend the 3 month claim period so new customers are not disadvantaged because they could not claim in time.