If your plane or train is late, you do not need to call us. In airports and train stations, everything is planned to deal with these delays.
Your train is late ?
The French train company is doing its best to take you to destination.
If your train is a few minutes late, the bus might wait.
If your delay is higher than a few minutes, you will be registered on the next bus if there is one planned (no need to exchange ticket or to call us). 
Your plane is late ?
The airport staff will do its best to help you (no need to exchange ticket or to call us).