Welcome to the forum and thanks for your post!
I'm sorry for the problems you're having with your BT Infinity service and that you have had these problems since November last year. That's a long time to be having issues.
As this has been going on for so long and you feel like you're going round in circles we will pick this up and manage your case from here. Click on my username here >> RobbieMac << and you'll see our contact link on the left hand side underneath my profile picture.
Whenever you send your details over you will join our email queue. Whenever you reach the top of our email queue one of the guys will be in touch to help. We deal with cases strictly in turn as we receive them.
We've had a look at this and we can now see a case manager is involved and are keeping ownership of this.
Please keep things thread updated on the progress and if you do have any more problems we'll step in.