now that cream are saying no, i think you gotta take it to the next level.
get to the highest guy in the company.. treat it no different to just like you would with a commercial organisation..
also have you sent them an invoice? often with these ppl chrissi will ask for the accounts department and get the cash direct without the arguments/bullshit.
in fact, don't even bother phoning anymore.. send to the main guy a really official looking letter. look round the net for some good templates for complaining to companies... at the end of the day it's a service you provided and you havent been paid... think about who you signed the agreement with. if it was with cream it's easier. but if it was poland, well it's going to be a little more difficult, but it was still in 'creams' name, so you would expect them to hold some responsibility... you'd word your letter to the main guy accordingly then, not being too in ya face, but telling them how you 'hope' they'll sort it out cause you'd 'hate to think they run their business like this'..... get the grammar right, friendly but firm, and oh and don't forget to send it recorded....
then if a few months down the line that isnt working.. speak to your solicitor and see what the options are.. that's when it gets really serious..
i think the key now is to take the 'music trust' out of the equation and get a serious plan of action.... treat it like a game, almost like a challenge too.. you'll sort it mate, i promise. as long as you start to take it seriously and do things fair and by the book
i'm sure you know this anyway heh :)
good luck man