Just Flight have a survey they'd like filling out, it took two minutes of my life and I get the Battle of Britain Hurricane download in return.
However, if two minutes is too much of your time, try going to
http://www.justflight.com/product.asp?pid=519, add to basket, checkout, log in with your justflight details (or create an account if you don't have one) and add the word SURVEY in the discount code box, click apply code and you should see the price change to £0.00.
If that didn't work, then you'll have to do the survey - a link is from their homepage.