Must admit the O2 online sales team do seem to have a big problem with being out of sync with the website. I can only assume they are managed by two seperate departments that don't talk to each other very effectively.
Last year, I had problems whereby I needed to upgrade and asked for the LG Chocolate phone, which was advertised as for sale and in-stock. They told me it wasn't even for sale any more and hadn't been 'for weeks'. Then I came back to them and asked for the (newly released at the time) Samsung E900 but they said it wasn't in-stock yet, even though the website indicated it was. After two more expected 'in-stock' dates which didn't materialise, they eventually sent it - a month later.
I don't think its anything sinister. The impression I had was simply of a bolted on website which wasn't maintained very well. If they are guilty of anything it would be a slightly cynical approach by suggesting something is in stock to get the buyer hooked into the process. A bit like employment agencies advertising jobs that don't exist.
At the time I sent a complaint to O2 and to their credit they were very fast at responding, courteous and apologetic. I didn't push for a discount or extras but I'm sure I could have done.
I was hoping the process had improved a little as I'm about to upgrade again. Maybe I will just pick an older, less fashionable phone that they are bound to have in stock