Bonding and suggestions for receivables

I am on a private job in ma for subcontract work that I was not paid for 220k of work completed. The total project worth is 20M. I was informed there is no bonding on the job. This is NOT public or state work. One would think that the laws would require the construction company to have bonding but I have been reading that only public jobs require this over 25 K. I know procedures are mediation and arbitration but is there anything else I can do besides liens? Thankyou