Found this:-

Call your airline representative as soon as you realise you will no longer be able to make a scheduled flight. Have on hand your flight confirmation numbers and the information from the credit card you used to purchase the tickets.

2
Explain your situation to the representative clearly. State why it is impossible for you to fly on your scheduled flight. Legitimate reasons recognised by most airlines for ticket refunds include illnesses, jury duty or family deaths. Offer to provide evidence of your situation, if needed.


3
Present the proof of your situation to the airline in the manner requested. This may include mailing in documentation or presenting it in person at a future date. Documentation may include doctor's notes, death certificates or legal summons. In the case of illness, ask your doctor for a note that explains how your illness rendered you unable to fly. While small illnesses such as a cold might not be recognised by an airline, a serious condition that presents health risks to other passengers is normally acknowledged.

4
Ask for a clear explanation of the conditions of the refund. Some airlines will refund the money directly to your credit card, but others might only allow you to book a new flight. In the case of airline credits, be aware of the penalty charges, blackout dates and other restrictions which might apply.

5
Ask for a refund of the government taxes. If your request for a full refund fails, ask for the taxes you paid when you purchased your airline ticket. Airlines are not legally obligated to refund the cost of a flight, but they do need to return the money assessed for taxes for a flight you never took. Refer to your original receipt for the exact amount of these taxes.

6
Negotiate with the airline to transfer the funds spend on the unused ticket to a new flight. Many airlines may be unwilling to refund you the full amount of your ticket when you miss a flight, but they might allow you to put that credit towards booking another.



Did you pay for the flights on a credit card Might be worth getting them involved too if you did