If I find a new employer, what can I do? Am I supposed to leave China now?

Hi everyone,
I applied for a job and they accepted me at first. They asked me to get the release paper from my previous employer, I got it and I gave it to them. Then the new company decided not to give me the contract. Now I am left with a release letter and with a Visa that will expire in October.

Is the release letter official for the PSB or will it count only if it is given to them?
Thanks