Ex-Telewest, ex-Cable London customers!
AJ is in the right of it. VM is NTK rebranded, which merged with Telewest, which took over Cable London.
Cable London was brilliant back in the day, with a fast reliable service (uncontended in my street) and superb Scouse-accented tech support who answered the phone promptly and would take all the time in the world to solve my (mercifully rare) problems.
But with demand comes contention, and this is at the heart of it. Last century I was probably the only Cable London broadband customer in my street. Now I can see typically see eight or 10 wireless networks in the evening, and speeds up and down are therefore piss-poor.
A contention ratio of 20:1 means there are potentially 19 other customers competing for bandwidth (and any may have more than one workstation active -- we often have three or four). If throttling the big downloaders is needed to keep response times within the realms of reason, that's all right by me.
What is unforgivable are the increasing frame drop-out and black-outs on the Virgin Media TV service, and the glitchy phone calls. I'm surprised nobody has yet mentioned this.