What can I do to contest/appeal a complaint filed by a homeowner for work that was done by a different contractor

Home improvement issue: I own a California corporation that holds a CSLB license. My corporation was hired by a home improvement franchise to administate the employee's of the franchise. The previose license had a complaint called in. In an attempt to maintain customer satisfaction for the trade name my corporation went out to address the issue. There was no writen contract, but a verbal agreement made between the home owner and my corporation. My corporation agreed to supply the need labor to correct the 4 year old issue and the homeowner agreed to supply the materials needed. The home owner has now, after we have already provide approx 1500.00 worth of labor at no charge to her, decide that I should supply materials at my cost. I said no. What is my legal responciblity here? The home owner has filed a complaint against my license. I did not do the original work, it was contracted with a differrent contractor. I have copies. - Is this your question? Add additional information