Not surprised, the stories of artists signing for X and getting never properly compensated (either for X or X-extended-to-anything-else) are countless.

And there's little you can do, unless you can nail down the exact culprit to a specific court.

For example: Apple is selling my music, without my consent or without paying due royalties. If I go to them they say "we pay royalties to the distributor", the distributor says "we only deal with labels" and my label has gone bust. Another label now has the rights. They don't know me. They don't have a contract with me. They have a contract with a deceased label that sold them rights they never acquired. So... yeah, it's never going to be fixed.