For such purchases, the remaining cash portion must be paid for by a debit or credit card. If you choose to pay with a credit card, you will be charged a service fee. If you choose to pay with a debit card, you won’t be charged a service fee.
Click on the link below to login to your Privilege Club account
https://www.qatarairways.com/en/Privilege-Club/loginpage.html
For further enquiries contact your local offices, contact details can be found in the following link https://www.qatarairways.com/en/worldwide-offices.html