After Greencard

My employer agreed to start the GC petition on my behalf with a condition that I continue work for the company 5 years upon GC approval. Without the contract, they will not proceed with sponsorship. So without any choice to get to - I agreed and signed a contract stating they lend us certain loan amount in $$$$$ and that we pay that amount by working with the company upon approval of the PERM, I-140 etc etc for a period of 5 years. Failure to stay would mean I have to pay $200 a month (x 60 months). The stated amount in the contract was intended to be paid for the Lawyer. But truly, the job offer exist for my experience in the industry. I did not physically receive the amount loan but I thought that was the payment for the Lawyer to work on my case. Without much thinking, I said OK I have to agree on this or kiss my sponsorship goodbye, right? Anyway, I know some Lawyer's opinion I read said any expenses incurred during PERM prep and filing fees should all be taken care of by Employer. But that wasn't the case for me.

So comes filing of I-485, I paid for filing fees for my family members but company paid mine. Until I got approved last year and 6 months later after approval, the company is not paying the prevailing wage determined by USDOL which was attested by PERM filling and I-485J bonafide job offer document file with AOS which about 23K$ more per year. Now that I am permanent resident, What are my options? Is the contract I signed with them legal or illegal? Can I quit the job and not worry about the contract? Can I make a retro claim of the unpaid wage since GC approval date? Not to mention, my Employer did not pay the LCA during my 2nd H1B renewal back in 2019 which is 12K$ more.

Anyone, who've been on the same case, please share. I know I'm not alone on this scenario, there are number of us former H1B's to GC's whom are being exploited by our employer.