I have the same problem they tell me I have new offers but when I try see it says the error message. I also received a letter telling me to move to EE as it’s supposedly the best network.
Logging into ee doesn’t work for me if I use my bt id details.
I managed to log in on the EE site for broadband deals but having used my address and phone number I was bounced back to MyBT as I was a BT customer.