you should be seeking some kind of compensation for this mate, I had 8/9 months of problems when my local UBR (at the time in Cheshunt) was overloaded, I used to get an upstream of about 10 max.... used to be great, people on the forum will remember well how arsey I used to be, with reason though
The real bugger was that the UBR is based at the bottom of the road from where I work, I felt like going down there and waiting for the next engineer to turn up so I could threaten them :P