First of all, I want to point at that capitaine train is a fairly good app for buying train tickets, the user experience is better than most app.
But they don not offer any customer service by phone, only email, which is highly inconvenient in urgent situations. Once you buy a ticket from them, you cant contact the carrier directly for support and have to go through Capitaine Train.
This is unacceptable when selling tickets.
nbarraille about Trainline Business EU