does the name of the city in the extention of the address improve seo result?
from companyname.waw.pl to companyname.warszawa.pl
where warszawa is the name of the city.
the searchers may narrow the searches to just one city.
So many factors being at play, I wonder if such a change would not be too much messing around.
Such a domain name change would basically mean that all previous SEO goes zero and you start from scratch. Don't change the domain name. Just make sure you have your company's physical address on your site. That would make sure you get included in local searches.
Replacing a domain name would be pretty much starting from scratch, an alternative would be adding a city subdomain: warszawa.companyname.pl for some legitimate reason, while not as powerful as actually committing a domain name it may do something slightly better than just having the city in the url of an articles. Trying this with many city name might look like obvious SEO spam to search engines, I don't know where they draw the line.
Just having your business address in a contact page that also appears in yellow page, yelp sort of directories should help the local ranking
Having a physical business address, entitling you to have a free Google Places Page is the easiest way to be could in local searches, those PO Box services worked for a while but I believe they will now rank poorly.
You can have the city name in the URL, it doesn't need to be the domain. For example:
But if your website is just about your company and you only have 1 location then putting it in the meta tags, title, ALT tags, Table Summary, body of HTML, and H1 tags should be sufficient. Also make sure you get links back to your website with the anchor text of the same thing you want to be found on search engines for(Same as your H1 and title tags).
Another good tip would be to add rich snippets of structured data which consists of your business address, phone, lat and long, etc. This will allow google to show you in Google maps and Plus. For more information on this see here:
Hopefully this helps. Cheers.