Assuming you actually have Windows version now (sorry I made that assumption), there's actually a similar thread about this with 31 pages here which may interest you:

http://forum.square-enix.com/ffxiv/t...al-CE-purchase

That thread differs slightly in that it originally started out with people with 1.0 accounts wanting to upgrade to CE with a 2.0 CE physical box, but the situation is the same as yours in that you/they have a standard account obtained via whatever method and want to upgrade it with a physical collectors edition.

One way that I believe may work (have to confirm this with someone else though), is applying a PS3 collectors edition to your account (assuming your current version is Windows) because that should then give you another 30 days free AND make it collectors edition. You can only have 1 Windows or 1 PS3 game per service account, but you can have 1 of each.

Hope that's some help or at least a possible resolution!