I was debated in March and April 2018 what could become the consequence of poor cooperation between train operators, when travellers from June 2018 could not buy one ticket including all the journey, lets say Copenhagen – Zürich via Hamburg, with the use of NightJet from Hamburg – Zürich.
After an outcry by German politicians it was understood that German Railways (DB) per kulance accepted to compensate delays, if the travel chain included a change between a DB (connecting) train and an ÖBB NightJet.
What came out of it? It cannot be told how many cases costumers have been rejected compensation. But in one case it was so.
In the case the journey started in Copenhagen via Flensburg to Hamburg, and here the two unfortunate travellers should reach the NightJet to Zürich (45 minutes connection). They had two tickets from a DB sales office: One from Copenhagen to Hamburg, and one from Hamburg to Zürich. But DB Regio cancelled the delayed Flensborg-Hamburg train in Neumünster, so the travellers lost the night train in Hamburg. They decided to stay the night in a cheap hotel room in Hamburg, and continued by day trains to Zürich next morning.
The standard procedure was followed, although request for compensation only for the hotel was made (and not for delay). October 8th (but dated 25.9.) DB denied the request and would not compensate a cent. “There was no travel chain”, DB announced. This was clearly against the public understanding. The case could have stopped here with some dissatisfied costumers, but the case was send to ÖBB, where the legal department made their case against DB on the “internal lines”. 15.11. (but dated 2.11.) the costumers got a new letter from DB announcing the refunding of the hotel bill. However, DB is not accepting the journey as a travel chain. So far we should believe the mutual understanding from April 2018 about kulance is maintained.
In such cases, the Eisenbahn-Bundesamt can be of great help. DB immediately compensated once ordered by the EBA, after my direct appeal to them had no affect.
The situation is about to improve, new EU legislation on rail passenger rights in the pipeline:
https://ec.europa.eu/info/law/better-regulation/initiatives/com-2017-548_en