Only guarantee is the bees will be gone. Maybe covers 2 weeks, going back for stragglers. After 2 weeks, they are gone, warranty is gone. I never do the repair and recommend other beeks to never do repairs. Do both, and you are liable for the new swarm. Let a contractor do the repair, or the home owner. Then you aren't responsible because you didn't do the repairs. The contractor isn't responsible because he knows nothing about bees.
The home owner pays for the new swarm.
PS. I do tell the home owner to be sure the cavity is filled with insulation, or something, as sealing it off is nearly impossible. They need the open space to build comb and will not use the area if no open space is available. If the space is left open, they will rebuild through a 1/4 inch entrance 20 feet away.