I can only second that. In Europe and the Far East they are very reluctant to help you as a non-rev. If you have a ZED ticket to a certain destination, it can be valid on several airlines, that’s fine. But if you want to change your destination, even if it’s within the same zone, they want to see exactly that ticket (which you don’t have). Make sure you have all the tickets required. As said before, they are reimbursable, but you may pay a service charge (10 Euros per ticket at my airline).
It’s a shame, how we treat each other in Europe, but it probable has to do with jealousy, which is the base of socialism. Have a good trip.