California Code, Civil Code - CIV § 919

The offer to repair shall also be accompanied by an offer to mediate the dispute if the homeowner so chooses.  The mediation shall be limited to a four-hour mediation, except as otherwise mutually agreed before a nonaffiliated mediator selected and paid for by the builder.  At the homeowner's sole option, the homeowner may agree to split the cost of the mediator, and if he or she does so, the mediator shall be selected jointly.  The mediator shall have sufficient availability such that the mediation occurs within 15 days after the request to mediate is received and occurs at a mutually convenient location within the county where the action is pending.  If a builder has made an offer to repair a violation, and the mediation has failed to resolve the dispute, the homeowner shall allow the repair to be performed either by the builder, its contractor, or the selected contractor.