Anyone else having problems like these.

I know Tiscali throttle P2P etc during prime time usage, but now they seem to be blocking access to steam at the same time.
At the moment my steam account will access no problem all day, then 17:30 till 23:30 no access at all (offline only) then all OK again. Internet access during these times seems unaffected.
Not sure if this caused my kicking from GTR evo race on Sunday as I was having to run steam offline, guess I'll find out this Sunday. Takes the edge off looking forward to the race somewhat.
Raised a ticket with them, but the last time I had problems took 8 months to sort out.
Any advice on good UK ISPs as may be requesting MAC code if no solution forthcoming pronto.