Looking at the screenshots in posts 7 and 8 your problems are due to you having initially used an extension wire to connect your modem with - as a result I think Openreach's DLM system has capped your maximum speed as their initial tests showed you had a poorer line than you actually do.
Line 7 of message 8 showing the troubleshooting page/Maximum data rate suggests your line could actually achieve 77MB.
However, Line 6 of the same shows you are syncing at 63.5MB and message 7 shows your IP Profile as 61.53.
If you wait a while then Openreaches line management system should hopefully autmatically realise your line is capable of faster speeds - otherwise you will need to contact BT and see if they can do a DLM reset for you.
In real life browsing, you won't notice the difference though.
If Openreach were to send an engineer out, I would expect them to replace the LJU2 box with a new NTE5 so ou woudln't need to use a filter - not that will necessary improve your speeds.
Thanks for all the feedback, I contacted BT via the online chat at Customer Help on Friday and they did a DLM reset for me. Speeds all weekend were bumbling around 61-62mbps. I checked this evening and my HH5 is connected at 58045mbps and appears to be diconnecting intermittently, seems like a downward spiral!!
Waiting to chat someone online to get this sorted!! GRRRRrrrrr
Ah right, they said they did some reset on friday, I guess not! Random disconnects and a speed thats getting slower and slower Just come off the phone, Got a openreach bloke coming friday after a line fault was found.
Just an update, Had an engineer call today. He checked my lines back to the street cab and confirmed copper was ok. and everything was within spec. The engineer completed a DLM reset and my connection speed was still down around 63meg to his tester. He talked to the tech gurus somewhere in the UK (from the guys accient it was the Midlands), he confirmed I should have a faster connection than I was getting. He popped to the street cab (400meters away) and found a fibre port had an issue, He re-assigned a port. He then fitted an SSFP socket and now my connection is (drum roll) almost 80Meg!! Thanks for all the assistance guys!
After a few weeks my line has stablised at 19.999Mbps up and 79.999Mbps download. Not too shabby hey?