At a loss, BT can't seem to fix my problem.

Question

I don't know if anyone else has any suggestions but I'm at a loss here.
We've had nothing but endless problems with BT over the last 4 months and I'm simply lost now.
It started when me and my girlfriend recently moved into our new ground floor flat early January and an engineer came round to set up our infinity connection (we moved it with us, had absolutely no problems at last address). He got the internet working and said someone will be round later to fix the phone line. The engineer came round and fixed the phone line but in doing so, broke the internet connection and then left. We then tried to arrange visits from various engineers, none of which actually showed up. I was even told on 2 seperate occasions that "the work will be done without anyone having to come into the property. Someone is actually working on it now" which I found out later to be a blatent lie as no one had been booked to come round. An engineer finally came out to fix our connection 11 whole days after it was initially supposed to be connected.
Unfortunately, that was only the first problem. Now, whilst the internet does work and we do get reasonable speeds (35/10 wired) the connection will drop anywhere between 10 seconds to an hour at a time at random points during the day, mainly at peak times. This will result in the DSL light on the white OpenReach modem flashing or going out completely or, since we upgraded to HH5, the light turning Amber/Orange. As someone who works from home and also enjoys online gaming in my spare time you can imagine how frustrating this can be and is starting to have a negative impact on my business. BT seem to be at a complete loss as to what the problem is, although they'd never actually admit this.
These things have so far been ruled out:
Our hub was upgraded to a HH5 with the builtin modem (not a hub or OpenReach modem issue)
All wires have been replaced.
Phoneline from the flat has been fault checked which it passed.
The OpenReach socket (the combined DSP and Phonline one) has been replaced and upgraded.
Connection has been completely restarted several times.
I'm not too good with the technical side of things but I did notice in the HomeHub settings that I'm getting a Noise Margin of - 12.8 / 17.6. That isn't good, is it? From what I can tell it should be around the 6 mark? Could inteference from someone else's flat be causing these problems?
EDIT: Oh, just thought I'd add that the actual phone line has been crystal clear the entire time with no crackling or dropouts.
EDIT 2: Something I've just noticed: When my line is stable and working correctly, the first value in the Noise Margin drops significantly (currently hovering around 3.6 / 17.1). This is indeed starting to look like the problem.
After spending roughly 4 hours on the phone to BT in the last 4 months (they REALLY enjoy putting you on hold and moving you between departments) I've given up and refuse to call them again.
This is my last ditch attempt to get my problem fixed and any help at all anyone can provide would be very much appreciated!
Thanks in advance.

Answer 1

Hi Insignia,
Thanks for posting!
I'm really sorry for all the problems you've been having since moving into your new house.  It doesn't make great reading to be perfectly honest 
No need to worry as I can help sort everything out from here.  Click on my username and under the "about me" section you'll see the link to get in touch with us.
Please include the link to this thread when you complete the form and whenever we've received your details we'll take it from there.
Thanks a million,
Robbie
BTCare Community Mod
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