You are entitled to free assistance at the station and on the train to get on and off and to make a connection.
Neither the railway undertaking nor the station manager can refuse you boarding because of your disability or reduced mobility, except for safety reasons. Should this be the case, they must do their utmost to offer you an alternative transport solution taking into account your accessibility needs.

To benefit from this assistance at the station, inform the station’s assistance service and the railway undertaking’s assistance service of your needs at least 24 hours before your departure. Please note: in some countries this period may be extended to 36 hours.
Respect the time of arrival at the station which was communicated to you.
If you have to travel with different train companies, check with each one.