We did casework as a sub for two contractors in Louisiana for a hospital medical offices. Job and punchlist completely finished end of December. Partial payments made to us. We received a change order from each of them saying because we were late, they were charging us between them almost $5,000 for supervision fees. Is this something that is legal? Nothing in writing from them to show us how they can charge these amounts and take them off our contract balance due. Please help