Unable to give correct information

I bought my mom's ticket with my credit card. When I bought it I got told as the ticket and the credit card don't match I will have to go in and sign some form and show them my card. Not a problem. Before that can happen though my bag with wallet in it and said credit card goes missing. I order a new credit card and my mom collects it in SA and will bring it over to me. Obviously I cannot now go into Cathay offices to show the card so I get my mother to phone the branch in SA. NOT A PROBLEM they say. She only has to have her flight itinerary, no need to show credit card AT ALL. Today when she wants to check in. Suddenly the credit card needs to be produced. She shows them my new credit card but this is not good enough as the new card's numbers don't match the previous one. We explain we phoned and what we got told. They can't believe someone there would tell us that. So my brother HAD TO BUY A NEW TICKET with his credit card and they will reimburse me in TWO TO THREE WEEKS. If this was negligence on our side then I would understand but we did our due diligence and we checked to make sure.