Consult with your state's environmental police and department of natural resources. Ask them who they recommend in your area. If they won't say, then press them for an unofficial statement. At the very least, you should ask about any potential wildlife law violations they have been cited for. Be careful of anyone who says they are going to spray something to drive the animal out.
Some states do no allow chemicals to be used on wildlife.
How often are the traps to be checked. Remember some states require the trapper's eyeballs to check the traps each day. Ask about the laws in your state. Finally, ask yourself some questions. If not then don't blame the NWCO for when something goes wrong.