[haa416]

My mother is old lady was flying from Cairo to Toronto through Frankfurt airport on Aug 2 , 2011.

The lufthansa ticket was fully confirmed HK status on all connecting flights.
She received two boarding passes from Lufthansa agent in Cairo airport.
When she got to Frankfurt airport, Lufthansa gate agent denied my mother
to board on flight to Toronto because the flight was overbooked. He was rude agent and refused to board my mother although he knew these facts:

1. She had valid boarding pass (FRA to YYZ) issued by Lufthansa agent in Cairo airport

2. The boarding pass has a status Stand By although the ticket was completely confirmed all the way.

3. My mother is old lady with wheelchair on the ticket and she was waiting her connecting flight to Toronto and she does not have visa to enter Germany

Lufthansa agent has made a great mistake and caused my mother a severe pain physically and emotionally because she had to sleep over night in the Frankfurt airport waiting for the next Lufthansa flight the day after (waited 24 hours in Frankfurt airport from 2:00PM on Aug 2 to 2:00PM on Aug 3)
She received care and meal during these hours and EUR 15 voucher but overall she had really bad experience with Lufthansa

Now after she arrived in Toronto on Aug 3, I am looking to file complaint against Lufthansa and submit claims for the delay/denied boarding.
I need an advice on how to

1. send complaint to Lufthansa and to what Lufthansa office
2. what kind of claims we can ask in terms of compensation

I have all the ticket information and boarding passes

I would appreciate any advice or suggestion

Thanks