To avoid this frustration in the future, perhaps it would make sense for BITB to make it CLEAR on their homepage (or on the purchase page) that a Licence purchased is SOLEY for one specific platform or the other and is NOT cross gradable for free? This doesn't excuse your argument that MANY software Licences offer dual platform support for free but it does put BITB's position on this matter clearly upfront .... which is not the case now.

I feel your pain Dave.