The thing is Spirit, everyone knows you and everyone likes you, and knows you for the honourable soul that you are. You usually attend four soul events EVERY WEEK, two on a Friday and two on a Saturday, both supporting local events and travelling to national ones. You're also the sort of youngster we're supposed to be encouraging onto the scene, according to just about every thread on here. You're a clever guy, not to mention an obsessive Scorpio who won't let it lie. They have so picked on the wrong bloke here.
If a promoter had dared to hoik me out of their event because of THEIR mistake, and eject me publicly, in front of a queue of waiting punters, making me look like a complete c**t, then I wouldn't rest until I had their blood.
But that's just me obviously.
You've written twice, now write again giving them 7 days to cough up and offer you an apology for their mistake, else you take them to court and claim damages, which can be done quickly & inexpensively online. Don't forget to include a note of the hours you've spent on this already, charged at your normal geek rate, and make it clear that the clock continues to tick for every second they delay paying you.
And if you should need any help with the process, removing horses heads etc, you know where I am love.
T x