How long have I got to make a claim for refund?

Refunds 

Refunds must be claimed within 28 days of the ticket’s expiry date. The expiry date depends on the terms and conditions of the ticket you have purchased. 

If you have bought your tickets on this website, you can check the terms and conditions of your ticket by loggin into My Account and click on the ticket for which you require a refund. The conditions relating to that ticket will be displayed.