router up but internet down

[#1]

So this morning when we tried to go online we could not connect to the internet/emails.  Last night was no problem, we connected fine, but come this morning - nada
I spoke to a very nice chap this morning @  PN who tried various tests and eventually said he would reset the SNR(?) and we should find things improve over the next 48 hours. (edit: so apparently this shouldn't have been done in the first instance?  is that correct?!)
we still have zero internet. the Router will connect and is authenticated, and I can even ping but the ping results are very intermittent
the first server beyond my router (router: pings 100% <1ms) is 195.166.128.194
ping times to 195.166.128.194 either succeed in between 14ms and 34ms, or I get Request Timed Out.
with ping 195.166.128.194 -t
half the results will be Request Timed Out
My neighbour who also uses PN connecting at the moment via 195.166.128.187 and has no problems at all
I have tried different routes, different filters, plugged into the master test socket (up in the loft!), no joy.  The chap at PN did say there was noise on the line, which I could not hear, but trying some phones in the test socket and BT quiet line test I could hear a hum.
Is the hum really causing all these problems?  I have an engineer coming to site tomorrow, hopefully we wont be charged
I managing this on personal hotspot on my phone via 3G, and lets hope my usage limit does not dry up!
But through all this rant, what I really want to know is: what has changed since last night?
thanks
John

[#2]

Had a BT engineer (VOICE) out this morning, and when he tested there was no noise on the line. (why does that always happen?)  but he could see that even though the router was connecting, there was no internet.
I would try the speed tester and http://usertools.plus.net/@gateway, but I can't get any internet 
Apparently it is being escalated to a BB engineer

[#3]

I've just tried to remotely reset the port you connected to.
Can you restart your router and let me know if that's made a difference.

[#4]

Hi Chris
thanks for the reply, sorry I missed it earlier on - must switch on notifications!
I tried a restart of the router, but it has made no difference at all.
We are experiencing a 55% packet loss between my router and the gateway, and when I listen on the line there is a humm.    Isn't this meant to be a short to earth or something?
there is no packet loss to my router with response < 1ms 
We do have a call to an BB engineer apparently, but I have no idea when that will come through.
Also, any PN staff who read this, could you make sure I have SMS notifications turned on for my issue?
Many thanks
John