I have bought all my 3g phones from a couple of online shops like www.mobiles.co.uk and the last 2 came from onestopphoneshop.
2 things to note of interest. Firstly, onestopphoneshop used to have a terrible reputation and yet I have not had a moments trouble with them.
Took my last phone out with them on the T/T 600 package and everything they promised would happen did. The half price line rental for 3 months from the network and so far 2 cashback payments, all delivered as promised.
Secondly, in all the time I have had a 3g phone(bought online), anytime I have had a problem with the phone I have taken it to a 3 shop and either got it repaired or replaced, notwithstanding the fact that I bought the phone online from someone other than 3 themselves.
ps. I have to say that the E1000 phone I have found to be the most reliable on 3, no dropped calls, reasonable battery life, a great sound and ok ok a so so camera(hell one cant have everything, can they? well can they?!)