I am on a O2 direct retention deal formerly from a retail deal O2 500/100 and called O2 just now and they confirmed the following:
All new retail (normal resellers like mobileshop, etc) and online (via O2 direct via phone or online) contracts right now no longer have 08XX calls taken from inclusive minutes.
From 1st August at the latest (she originally said 1st July, best to assume July) all current contract customers will no longer have 08XX numbers free (except O2 CS calls) and 0870/0844/0845 will be charged with letters going out giving the 30days notice, excuse was it was never really free but on some kind of promotion.
Sorry, considering past instances of things like this I should of mentioned, it REALLY helps if you used these numbers in the past as it proves a detrimental change to your contract usage.
Although really it is a change of T&C within the contractual period nonetheless, what you can blag however is what the forums are for however and hopefully people will provide useful information.