A fair contract necessarily has reasonable dismissal procedures and an independent arbitration option.If in the first place you'd signed such a contract you could have insisted on its clauses being adhered to.In the event of a stalemate,you could have reported your workplace to Beijing for arbitration.Of course,your employer wouldn't want that,so the breaches would have been rectified in a jiffy on the spot.
But your contract wasn't fair,so you were out on a limb.Even though your employer had broken his side of said contract,you were powerless to force him to rectify said breaches.
So you did a runner,a coward's way out,and you've been taken to task for that since.Your justification for doing a bunk is unacceptable.
What you had posted about being illegally employed is untrue,and you'd neglected to say you'd signed a contract before doing a runner.
By the way,if you knew the contract was illegal in the first place,why did you sign it?
I've been treated badly before too in China.But unlike you,I faced the other side,and tried to improve my lot by forcing the employer to obey what he had signed.It worked,mainly because my contract was fair,unlike yours.That was your cardinal error!