This is a BT residential customer to customer forum. Your post does not go to BT. The only BT staff are the forum moderators who do not necessarily read all the posts.
You won't stand any chance if you don't post more information than you already have. If you supply what the problem is then somebody may be able to help.
Have you just had infinity installed? Did the engineer show you the connection was working before he left? Any lights on the hub? Did you try a factory reset?
Do you have any other sockets in your home which are in use such as sky? If so they also need to be filtered
If router flashing red sounds like no connection. I think you need mod help and they will post a contact us link when reading this post probably tomorrow.
After completing the email NOT PM then you join a queue of other customers waiting for mod help. The mods will get back to you in 3/5 working days either by phone or email