I'd do a search if I was you. there is either bsplayer lite or diceplayer on the market. those play them OK. that's your only choices.
I have this exact problem with mine too. on 3 and stock phone
never had a acceptable answer for it really. i have just taken to putting it in flight mode and back out again and it always works.
So ya either really unlucky with your handsets or three UK really does have a problem with the phone. I'm back in lincoln this weekend where I get the signal problem. So will test the *#*# thing and report back.
For me I get 6mb+ from some masts but on my actual H+ mast at home I get about 3mb from midnight and in normal working hours its about 200kb/sec as theres just too many users on my mast as I live on a raf base