I'm a subcontractor who finished work in California in early July. Sunbelt rentals overbilled me, and has now placed mechanics liens for unauthorized charges on the property owners, which is placing me in breach of contract and holding up payments to me.
If Sunbelt's lien is improper, you can obtain a mechanic's lien release bond, which will require Sunbelt to release the lien.
You should consider paying the undisputed amount (and obtain a waiver and release based on the amount of the payment), bonding around the claim (which will be less as you've paid the undisputed amount) and then litigating over the disputed portion.