Giving them their money back is admitting that what you have done in having the group was wrong - and it's putting your booking policy (and your freedom of speech) into the hands of a couple of 'good ol' girls'.
Fascinating to see what a question like this drags out of the woodwork.
Not sure whether John Mackenzie is dictating what should be performed or commenting on the standard one is valid - the other definitely isn't
Jim Carroll