If you had an account with Netflix, you don't have to open a new account. You just log into your old account using the email address and password you set the account up with originally and then reactivate the account.
Thats not BT's flaw that would be Netflix's as they design and release the App Bt just has the ability to upload it to the youview box.
This is BT not Talk Talk but anyway lets get back to the FACTS....
"Because of data privacy issues you can't use the same email address, for Netflix with BT, that was previously used for a subscription direct with Netflix in the last 18 months. This is because the previous subscription account information is still saved on the Netflix system, and, is held for a period of 18 months. This is part of EU law but it is under review and this may reduce from 18 months to 11 months"
Thats EU law granted we probably might not be in it much longer but there you go