@Fluffy Bunny Re: and in the UK ?
" I assume they notified you of these limits in the advertising before you signed up."
No, they didn't. Back when I 'signed up' (when it was still NTL), they had a clause that said they (paraphrasing) "had the right to take technical measures to protect their network from customers who behaved in such a way as to ... blah, blah, blah ....". This seemed to be about hackers and script kiddies and snoopers etc. which would be a perfectly reasonable thing to do, of course. The throttling was only revealed when many people noticed distinct throttling characteristics and talked about their experiences on various forums, thus reaching the obvious conclusion. Virgin Media refused to admit that they were throttling and made nebulous comments about 'protecting their network' before finally admitting that they were throtting and writing clear terms into new contracts.
I don't mind the data throttling and would say that the current way in which it is done seems reasonable and is clearly stated in the T&Cs. What I don't like, and do mind, is the lies and obfuscation that went on before they started being honest about it.