A truss company sent me an email that stated " attached is your invoice for the balance of the trusses they are in production right now, the balance due as of today is $13,750.00; included in the amount was a charge of $200.00 for Notice of Commencement that was not needed, that was disputed and balance due was adjusted to $13,550.00 balance which was paid by personal check, paid in full written on check in memo area of check and was picked up be their courier at agreed upon location in Miami, Fl. The check was cashed; about eight days later another invoice was received was received stating I owe another balance of $20,764.32 because it took me 3 years for final go and costs of material had gone up; that amount was also disputed and they reduced it to $16,321.00. Free Expert Opinion, please. Original contract was for $27,300.00 with sales taxes. What are the Terms of Service?