I am an o2 online customer, here is the story :

-I made my order online (of course), and choosed saturday delivery as i'm away on work weekdays. That costs me £13ish but I do not remember exactly. The phone did not arrive saturday, i rung them and i have to chase the parcel and they were unable to trace it. I got to chase it at DHL office and got it after 2 weeks. I made a complaint and get refunded the delivery.
-i was charged from the date i made the purchase online, that is to say i was charged during the 14 days i did not yet had the phone . Fine!!!
-and finally, I got charged for 13 standards texts messages while I have 50txt allowances.
-as an online customer, you do not have the right of phone customer services, you must use the web and email to solve your problem

they are a joke, I think I'll avoid them in the future