I have a subcontractor who bid an amount to work on a residential renovation. After beginning work, 6 weeks later, he stated that he underbid the job, and "revised" his initial bid to 2.5x the amount in a text message. I requested a meet to discuss this matter, but he did not meet with me until after the original agreed amount was paid in full, and over 90 days after saying he under bid. I never agreed to his revised bid, but was willing to discuss it. Furthermore, he is now requesting payment for items he states were "extra," but at no time during work indicated the items were extra, presented a price for those items, received approval or billed or provided any change orders. He is now demanding payment and threatening a mechanics lein for these extras. I am an honest person, and feel I am being taken advantage of. Does he have a case?