this happend to me two years ago, I was able to catch the charges quickly as unbilled transactions on my Mastercard before the flights had taken place. I called Aircanada Reservations with the ticket numbers which were on my mastercard line entry and asked them to please fax me a copy of the particulars, which they did. I then went to my local police service, filed a complaint, and then phoned my credit card company and AC again to tell them I had not purchased the tickets, who the police officer was that I made the complaint to, and his phone number. I could tell AC wasn't too happy about me having involved the police myself, but I thought too bad. The police officer contacted the calgary police, and a calgary police officer detained the lady after she provided the ticket to the gate agent, but before she headed town the gate to the plane. She was held for three hours and said her husband had bought the ticket from a discounter who had an add in one of the free papers you find in the big cities, as such she was let go, but AC refused to sell her another ticket and she had to purchase one from Westjet to get back to Toronto. The Calgary Police actually called the Toronto Police, and about three months later my local Police Officer called me give me an update that they had a large number of very similar frauds and that the Toronto police had arrested an individual who was taking numbers of renewal cards as they were produced before they were mailed out.