Another Day. Another 72 hours. And No Response to My 3-week old "Question"......

[#1]

First off, thank you Adam for your help, your intervention does seem to have gotten things moving slightly, albeit slowly.
I am dissapointed that Plus Net are choosing to sit on this and do nothing for another 24 hours.
Looking at the test results posted on my ticket, those from 1 week ago look identical to those from today, meaning that my line has been stable for somewhat more than 48 hours already.
In fact the only area of multiple stops and starts I can see is from last wednesday / thursday, and that is right around the time where I would have been plugging various routers in to various sockets to see if it made any difference (at Plus Net's request).  So actually, my line has been stable this entire time. 
One controlled "end session, start session" event in a 24 hour period is not what I would call "unstable" or are you seriously telling me that if I choose to re-start my router for some reason then PlusNet / BT will automatically decide that my line is "unstable" and cap my connection speed?
I think my router also tends to drop the connection if it's not in use, so should I change the settings to tell it to try to maintain the connection as long as possible, even if it's not in use by a member of the household? 
How will this affect my usage stats? 
Or should I turn off my router when I leave the house / go to sleep to make sure that it clearly shows as a deliberate disconnection?
Basically, can you give me an idea of how many disconnections in what time frame qualify as "unstable" so that if I need to move / close / restart my router for whatever reason I don't accidentally trip the software in to thinking I need to be effectively cut off for my own good?

[#2]

ignore my last comment, they have actually lifted the cap as of now, they've also changed my profile to a "manual change only" option so that minor fluctuations in stability won't affect my sync speed or max download speed available
shame it took a week to do something that is as simple as clicking an option box, but happy with the result
now i just need to wait a couple of days for my line to re-align itself with the new sync speed

[#3]

Adam,
Thanks for phoning earlier to discuss the BT engineer's visit today. As we discussed, he replaced the D-side cabling fitted a new filtered faceplate. He also swapped our line to another connection on the pole that isn't using broadband.
Connection has been stable, with no disconnections, since he left about 12.30. When he left the router connected at 3,776kbps and I was getting download speeds of around 2.2MB.
The return to my previous download speed hasn't lasted long though. Earlier this evening I noticed it was way back down to 304kbps, while the IP Profile/BRAS is showing as 2500kbps according to BT speedtester.
What's the next step?
Thanks,
Catrin

[#4]

Hi Catrin,
Apologies for the delayed response. As per when I called you it looks like the connection is still dropping. However as there is an MSO affecting you at the moment we are unable to progress the fault report that we logged for you individually. As soon as this is clear I will instigate further checks to be carried out for you. Please bear in mind that this may mean another engineer visit, but I will do all I can to avoid that.
Adam.