No such voucher exists for BMI flyers

I very much doubt you can pay to upgrade FRA-DXB on a miles ticket (what base fare are they meant to use?) and even if you could it would horrendous (in the thousands) and you'd miss - because they can't do it at short notice - one of the best bits, which is being met at Frankfurt by a car instead of being shoved on the bus.

To be honest, I didn't think LH was releasing 2 F seats these days because of the switch of the 747's from 16 to 8 seats and the refusal to offer seats to non-M&M airlines on the A380's in F. It could therefore be that 2F seats really weren't available after all.

(PS. One other way of doing the F terminal is booking FRA-ZRH-DXB with ZRH-DXB in First on Swiss. This gets you F terminal access in FRA. You can also do this on 'cash and miles'.)