When you go to the serp that is giving the wrong address, this should be displayed next to a small map:
The wrong name (linked to the other company's site)
Your address
Directions and more >> (may say Directions hours and more or similar)

Click the Directions and more link, and on the next page click edit this listing.

Dissatisfied comments I think are routed to the engineers who actually work on the algorithmic results, (searcher based) rather than whoever edits the listings (webmaster relations). If you don't have the links I mentioned, could you post the query that is giving you the erroneous listing?

__________________
The best way to learn anything, is to question everything.