So I had a strange situation.

I was taking the train from Nantes to Antwerp via Paris. I booked through Oui.sncf - first leg on TGV second leg on Thalys. Both legs in First Class. I purchased the ticket and it offered a 1 hour 9 minute transfer between stations.

My TGV train Nantes-Paris was late arriving causing me to miss my Thalys train.

The next Thalys train to Antwerp wasn't for another two hours. I asked the staff about compensation for the delay (getting to my destination 2 hours late). The Thalys became quite upset and said that I should have to purchase a whole new ticket because it was my fault I missed the Thalys train. I explained that my first train was delayed and she said it wasn't Thalys' problem. She told me any offer of getting on the later train was a gesture of their gift to me and ripped up my ticket in my face, but that's another story...

Finally I got someone from SNCF to help get me ticketed on the later Thalys train but they didn't have a seat for me so they offered I could sit in the jump seat.

Is this a known problem with booking through Oui when it is a "mixed" ticket with two different train companies? The website makes it look like it is a legit ticketing for both TGV and Thalys.

I would definitely avoid booking a mixed itinerary. And avoid Thalys at all cost -- VERY rude customer service agents.