Maybe my case is one of the exceptions but about 2 months ago, I lost my Vodafone RTG phone. When I couldn't find it, I bought one of the cheaper RTG phones in a Vodafone store. Had it about 5 weeks when I got a 3G phone from a friend, and since it had more features than the phone I had then, which was a Nokia phone, I started using the 3G phone. I contacted Vodafone Customer Care and told them my situation (lost my phone, got an upgrade, recently got a 3G) and that I wanted to give the Vodafone RTG phone to my sister, who was not with Vodafone, so I needed to get it unlocked. The CS rep took my details and within 26 hours, had sent me the unlock code for the phone.
Now, the thing is, I don't spend a huge amount of money on my phone every month, maybe €40 but they still sent me the unlock code after only a few weeks. I guess my point is that if you have a phone that is locked to Vodafone and you want it unlocked, then phone Customer Care and ask them for the unlock number. The worst they can say is 'no' and then you can just get it unlocked for €15 on Moore Street.
Adrian