want to sue attorney for return of retainer, senior abuse, and fraud for bringing in his own contractor to perform work we did not ask him to oversee

hired attorney to ensure tenant could not return to property after tenant has caused fire. This is a San Francisco property and we were going to make it a legal in law unit and planned to pull permits and hire a contractor ourselves. The attorney filed a 3 day notice to quit and spent our entire $7500 retainer on working on the permit and getting his own contractor to do the work. When we declined to sign the contract as we wanted to get our own bids he became extremely agitated and refused to return our retainer. He is now being investigated by the state bar. The owner of the home is a 90 year old woman.