I know some people have issues with O2 CS, yes I had a few but lately I've found they've got a lot better.
I bought an Iphone around 6 weeks ago and being rather techno-impaired had a lot of difficulty in getting started. Called O2 and sometimes mixed up my departments, but nonetheless the staff I spoke to transferred me quite cheerfully and I got myself up and running.
Had a problem with the manager of the store I'd bought the phone from, had to go back a week later after purchase about faulty headphones, left the store feeling pretty upset over his attitude and after recovering called customer services who were very sympathetic and helpful in lodging a complaint, still not resolved as yet, got a call from a lady from CS other day who was concerned that it hasnt yet been resolved and has offered to chase it up and get back to me.
This is not a grovelly post in case an O2 employee sees it, but just to say yes they can get things terribly wrong some of the time, but then again they can get it right.