Getting a refund from Czech railways?

Hello ​@edent 

I think that it is too late, in this situation you must have a confirmation from the train staff. 

Do you really think that train companies could make investigations only to refund a reservation? 

Yes. I do think they should investigate customer complaints. That seems like a reasonable thing that every other company does.

The operating company will have a record of which carriages were in service on that train. They should be able to confirm I am telling the truth.

The ticket inspector saw my 1st class reservation and didn't offer a proof that the carriage didn't exist. How was I supposed to know to ask for it?

​@edent 

Yes, for international trains the carriage numbers are manually entered on paper forms with carbon copies for every train, old but still working technology. Perhaps someone knows where these forms are stored.

I cannot further help you, you have the possibility to contact again every involved company, but, in my opinion, you are wasting your time.

IMO the operator should know whether 1st class was available or not, but if they wrote in the conditions that you have to provide evidence (I haven't checked), then you have no chance.