Cannot sync with ADSL2/2+ any more

[#1]

Okay this could be related to the recent line noise hassles I've had, but the line noise has gone and I can sync fine with plain G.DMT every time (although my sync speed is half what it used to be).
However if I change to multimode or ADSL2 or 2+, there's no hint of it remotely getting sync any more. I've been on ADSL2 for a little while but it's just died recently.
Thought it may be related to the downtime BT mentioned about 21CN in the Guildford / 01483 area which might cover me. That's apparently fixed now according to their site, but still no sync. When I lost it was about the time BT's issue started.
Currently syncing with G.DMT at 448kbps up, 3.6mbps down, with SNR Margin of 6 (average over the year has been 4), Atten of 38 (down from a 41 average over the year).
Any way to see what's going on with the profile or whatever. Is it just stuck now saying I can only get 3.6mbps basic ADSL? The Estimated Speed value on PlusNet says 3.5. I used to get 5 to 5.5

[#2]

I've run a test and can confirm there is no restriction to force you to ADSL1 across the network.
Do you have access to an alternate ADSL2+ modem you can try?
Did you try your own modem as the only device attached to the line from the master socket?
The tests do however show there is a degradation in the line over historical tests. This is not typically equipment you attached, but could be external joints of extension cabling. We can re-run our copper line tests with everything disconnected from your telephone line to see if we get the same result.
If you do, a non-appointed engineer will be dispatched (not chargeable). They don't normally need access and if they do, it will come back to us and we will arrange a appointed fault instead (though we will re-validate the line test first)

[#3]

Hi,
Just tried only the modem on the test socket. Same results. ADSL syncs, but still only at 3.5. ADSL2, nothing.
I'll disconnect everything for the moment and I'll use my mobile broadband for a bit. Feel free to run further tests (or do I need to raise a ticket?)
Cheers,
Tim.
Edit - currently reconnected for now. I need the phone and the broadband, what there is of it. Currently not dropping, though I'm finding making a phone call drops the connection which is kind of reverse of the problem I used to get occasionally.

[#4]

Ignore for now. Definitely a problem with the line. Lots of noise even with a single wired phone in the test socket. BT are in theory on the case.
P.S. Line tests I ran numerous times, both from web and 154, all came up fine, despite all the noise!