I went through the bolt-on change successfully for my Touch HD - changed it within 24hrs. A month later when I get the bill I find there's a £12.55 added extra bolt-on. Phoned up to query it and they gave all sorts of answers relating to it being a CPW tarriff and that I should speak to mobiles.co.uk, or pay an extra £7.50. Stuck to my guns as I'd not opened the SIM until I'd heard back from them about the bolt-on change, and that this was O2's mis-advice/cock up. In the end a manager is changing th tarriff back to what was originally planned i.e. bolt-on swap to mobile data.
So get the details of the person that changes the bolt-on and write it on the bill because it might all come back in the month 1 bill.
I guess that there's an incentive for mobiles to sell the text bolt on rather than data?
Every person appearing in my Dropbox referrals list will get a free speedboat or small family saloon*:Speedboat
*once the cash from my Nigerian goldmine owning ancestor clears in my account