Tickets not being sold online
I've been doing a dummy booking on Friday afternoon to fly Stansted-Vilnius on Saturday. For each of the flights on Saturday morning and afternoon, the app shows at least 4 seats available... but says even if it is just 1 person, a ticket can only be purchased at the airport. On other routes departing Stansted at the same time of day, online booking seems fine with no requirement to buy at the airport.
It's possible FR are trying to charge extra, but in that case, why not just raise the quoted fare ? I'm wondering if there is overbooking going on... despite FR's claims not to do so