A while back i upgraded to infinity 2 when it became available in my area. my speed went from 2mb download down to less then 1. after weeks of messing about bt came and changed the line to my house. for about 2 weeks after that my speeds went up to over 40mb download. the engineer told me we would have full infinity speeds within 2 weeks but that hasnt happened. speeds went down to around 8, last few days are down to less then 1. if i look onwebsite it is now saying i can only get standard broadband again???
although my upstream ip profile on my line is saying 20mb so seems there is something wrong with line.
and use this speed tester then scroll down the page and carry out the further diagnostics and post back a screen shot of all the results including your IP profile for up and down. This test must be done with a wired connection.
If you have a Homehub 5 can you post the stats from 1-12 by logging onto the Homehub management pages then troubleshooting > helpdesk. http://bthomehub.home/
If you have the Smart Hub, (Homehub 6) can you go to hub manager then advanced then technical log and post the stats. http://bthomehub.home/
Is there any noise on your phone line? Dial 17070 and select option 2, there should be no noise between the announcements.
Try connecting to the master socket/ test socket and if your problem is still there it could indicate that there is a line fault before the test socket on BT's side.
When you use the test socket make sure that any telephone extensions you have are "dead". There should be no dial tone at any of your phone extensions. If they have a dial tone it means you have star wiring and that is not good for Infinity and will need to be fixed.