You must respond to the Qatar Airways Support email you received explaining your circumstance. In some instances, we will be able to issue you with a web link where you can upload your supporting documentation online.
If this is not feasible then, the card holder can verify the credit card at any Qatar Airways ticketing office or the passenger can make a guarantee payment for the total value of the ticket at the check-in desk. This payment will be refunded once the verification of the original credit card has been completed. To confirm if this facility is available at your departure airport, please respond to the Qatar Airways Support email you received.
For further enquiries contact your local offices, contact details can be found in the following link https://www.qatarairways.com/en/worldwide-offices.html