Not giving them the money back just makes you a ticket tout.

There's such a lot of this kind of thing at T In The Park, etc. that they brought the limit on numbers each person can buy, and now they are pushing to stop reselling of tickets completely.

I'm willing to bet that if that ever comes in, so that the only way to dispose of tickets is back to the original promoter their booking fee will be non-refundable, and maybe even a % of the face value will be kept as an admin charge, so they really don't need any more ammunition.