I can see that many people have had the same difficulty as myself. I have returned my BT equipment but am still getting emails requesting its return . The same for my EE equipment when I changed address. Fortunately I have kept both receipts and by using the tracking numbers can see that both have been delivered six and seven weeks ago. How do I stop the threatening emails?
Call BT 0330.1234.150 with your receipts and they can update your account.
If you have receipts of posting then phone CS 03301234150 and they will be able to update yours account