Yep, thats what I did a few days ago.
10mb > 30mb for an extra £5 a month, soon to be 60mb(April)
I was going to do the same but it will cost me £11 extra when I called them. Not paying that much if I'm not getting full 10mb at off peek times. My free upgrade isn't due till July next year, I would have left by then.
(April)

