The problem Thalys has, I believe, is automatisation (I'm not sure the correct word in English). When I speak or write with them, I do it in Dutch, so language is obviously not the problem. However, when they send me automatic responses either by post or by email, then there are problems. The last two times, there have been big errors in their replies (sent automatically). I don't really have a good solution, but save all your documents, especially the incorrect ones that Thalys sends you and then you can send them copies of these documents as proof they have made errors.

I am travelling to Paris on Thalys on Wednesday and they tell me everything is all right, but I still don't know if both my wife and I will have seats since their email confirmation said we only have one seat!