Hi Chris,
Without being able to look at the actual listing, it's difficult to diagnose an issue like this one. If you cannot share your client's details (understandable) can you provide further clarification as to your initial description of the type of search you're performing? I'm not quite following, as it seems you are saying you are doing a search for your client's own business name and location in Google's main search engine and that this is bringing up completely unrelated businesses instead of your client's business. This should not be happening, and I'm actually wondering if this isn't what you mean by your description. Please clarify if you can.
It would be best if you could actually show me the search and results, but if you can't do that, further description would help a little. I'll look forward to your reply!