Those companies should be blacklisted! Aren't there labour laws prohibiting free labour in most countries? If you fly as part of the required crew, then you should/must get paid.
Aviation is a truely rocky path to reach the top. Few years ago I struggled with the CAA requirements which were about the change to JAR (no, I didn't panic!
) and most UK schools I came across were just trying to rip me off. But, there's no better feeling than to be on the way to work in the early morning...