Thanks for the update to my original post (re forum rules) - didn't realise I was giving too much away!!
The email I received from PB looked like it was from a generic "bt_com_openworld_support@" address so I didn't think PB would see any response
All the best
Have replied to PaddyB at the generic email address but not received a reply.
Infinity 2 speed getting slower, but strangely upload speed getting better.
Latest test on speedtest.net gives 38 download and 18 upload - half of the "up to 76Mbps"
Still no caller display or 1571 service.