Flair Airlines complaint: Credit Card Transaction

In Sept 2021, my mother had a brain surgery so I traveled from Toronto to Saskatoon and back. I had to change my return date to a future date because of my mother’s condition was still not stable. I called Flair Customer Service to help me change the date and they willingliy helped me. The customer rep told me everything was all set and my return date was set to the one I wanted. The rep charged my US Credit Card and we ended the call. When I went to the airport on the day of the departure, I was not allowed to check in because the person at the chek-in counter said I had to pay for the date change. I explained them that I already paid them on the phone but they said that transaction did not go through because Flair does not accept US Credit Cards (by the way my original booking was done with the same Credit Card which they refused for date change). Now, I don’t have any Canadian Credit Card nor I had Canadian Dollars cash. I tried to explain them this but they would not understand. Finally, I had to call my brother who lives in Toronto and had to get his Credit Card in order to pay for the ticket change. This experience shocked me and this kind of harrassment was a surprise where an international airline does not accept international credit cards. I tried to call Flair Customer Service to report my grevience but they would not take any action or even say sorry for the treatment given to me. It would be nice if they gave me some refund for the harrassment and say ‘SORRY’!!