Maybe surprising, but nonetheless you will find this in para 5 of EC1107/2006…
“Assistance given at airports situated in the territory of a Member State to which the Treaty applies should, among other things, enable disabled persons and persons with reduced mobility to proceed from a designated point of arrival at an airport to an aircraft and from the aircraft to a designated point of departure from the airport, including embarking and disembarking.”
This is para 6
“To achieve these aims, ensuring high quality assistance at airports should be the responsibility of a central body. As managing bodies of airports play a central role in providing services throughout their airports, they should be given this overall responsibility”
And para 7
“Managing bodies of airports may provide the assistance to disabled persons and persons with reduced mobility themselves. Alternatively, in view of the positive role played in the past by certain operators and air carriers, managing bodies may contract with third parties for the supply of this assistance, without prejudice to the application of relevant rules of Community law, including those on public procurement”
None of which excuses the unacceptable experience this lady had.