Packet loss on second hop - who fixes the problem?

ADSL with Web Tapestry. Fixed IP address. All been fine and rock solid for almost a year. About 10 hours ago suddenly lost connection, no changes here.
Router syncs fine and I can reliably ping my own static IP address but not the next device (which is in the same subnet) and in Web Tapestrys infastructure.
What I get is 50% ping failure. That is enough to break browsing and most services although DNS still works most the time and I can resolve IPs
Have changed router, microfilter, tried other PCs, already plugged into master socket. Nothing else left to test / eliminate here. BT Quietline test shows all fine and neighbours on same exchange have no ADSL problem. Web Tapestry have been responsive but call has been with BT for packet loss all day, Web Tapestry say the problem can't be in their infastructure - I'm not confident that BT are going to be able to find the problem and if not then what ?
Any suggestions or ideas please - or any more diags I can do ?

a traceroute would be handy

Yes but it doesn't show much and I didn't want to publish the IPs.
My router has a fixed IP and I'm pinging the gateway that it routes to - I assume that is in WebTapestys datacentre although reached via a BT pipe (no LLU in my exchange).
I get 4 or 5 normal ping responses of around 32ms then 4 or 5 request timed out. No pattern, sometimes only 1 or 2 then time out but never more than 6.
In to the third day of this problem now, incredibly frustrating as I can only rely on WebTapestry to chase BT and BT to respond - which they haven't done yet although they have had the problem for over 24 hours.
Apart from waiting what else can be done in situations like this ?
BT won't talk to me as I have no contract with them - the phone is working perfectly.

no data, no useful reply.

And to add a ping test shows nothing, routers will drop pings as they are a low priority packet if they are busy doing other stuff.

Hmm bit hostile !
Maybe I wasn't verbose enough with the description but I was on a 3G connection.
Just to close this off it was a hardware fault in the local exchange - what confused for a while was it only affected about 20% of the users in the exchange.
Time line as follows:
Problem started 6pm Tuesday.
Could only be logged with BT 9am Wednesday.
Escallated 9am Thursday (as no fix after 24 hours)
Engineer attended and fixed 10pm Thursday.
Once the engineer swapped the card all was fine, no need to reset router, ping trace showed what was happening as it went from 50% to 0 for about 10mins.
Yes of course pings have a low priority and can be thrown away but a default ping-t to the IP address that is the next hop from my router showed the problem perfectly and went back to 100% as soon as the hardware was swopped.
Kudos to ISP Web Tapestry who provided good feedback of what was going on, you can imagine the nightmare those with retail ISPs had who needed to speak to Indian call centres.