Respect to 3 ! We recently bought a 3 Mifi dongle. Had a load of problems with getting connected and then drop off. Got in touch with 3 via Jo_ who was already in touch with them. Got a very full and speedy response from them which - as well as the written reply - included finding out the mast we were connecting to, discovering there was a fault and re-setting the mast. Now things much improved. They also discovered that there was a mistake in their printed guide that comes with the Mifi, which explained why we thought we were getting no signal when in fact we were.....just.
So, yes, they seem to be doing their best, and can't fault their customer service....and it's not often one can that about customer service generally.