I did concrete slab for a storage facility. The owner used to be my landlord and he requested the work to be done. He asked for a cost in and I gave the price based on the square footage he told me ($10K). Once, at the job site, the square footage turned to be more than what he said so he verbally agreed to pay the difference (total of $12K). Now he is refusing to pay the actual amount. I want to know if I can lien based on the total invoice amount without a written agreement. Price was determined based on total sq. ft.