Help us improve our process for when you experience home Wi-Fi issuesx
We have put together a short survey to capture your feedback in terms of what BT can do when you experience home Wi-Fi issues. We would appreciate it if you could take a couple of minutes to complete a short survey. Read more from here, Fix my home Wi-Fi
Unfortunately there's no way of BT blocking a number on your behalf. You've done it the right way, only other thing you could do is deactivate voicemail or block 1571, but both have further ramifications if other people need to leave you a message.