Been having kinda the same thing from Virgin Media in the last 3 days, Sunday i couldn't use my connection at all, speeds of less than 28.8k & web pages taking 30mins+ to load, still gradually getting worse. I'm surprised I've got here.
Rang them & all I got is "you've downloaded too much your connection is being capped by STM" 4mb to 28.8k is a lot of difference from the 1mb it says on the site. Funny thing is i hadn't downloaded anything major since Thursday.
For you I'd do what Youstolemyname said.
I wrote this in another thread on the forum, My experience of Virgin Media at present is horrible. Every month there seems to be a new problem arising, modems giving up, 28.8k speeds as mentioned in the quote, getting charged £7 for them to say it was windows firewall (funny how it all works until 8am on Sunday & then all of a sudden gives up) Spent the best part of 4hours going through crap with them on Sunday.
When they finally came to the "problem" I say that very loosely as they blamed my horrible connection on me downloading too much so being in effect of STM, Funny STM that cycles the modem every few minutes or so, Tuesday is here now & it is still the same. If it does not get better by tomorrow then i shall be ringing again.