I'm planning a trip to Perpignan this autumn. There are some through Barcelona to Lyon trains which call at Perpignan. Oui. Sncf is currently selling Barcelona to Lyon advance singles for €29 on the website: bargain! But it charges €79 to board the same train at Perpignan to go to Lyon. Is it possible to buy the international €29 ticket and merely board at Perpignan or will Sncf staff prevent me from doing this? Will my "no show" at Barcelona result in my reserved seats being reallocated (the train stops at Girona en route to Perpignan).