It's really important that your business only has one Google Plus account and that it's the right one. You don't want duplicate accounts out there.
What happened was that Google Places/Maps was combined with Google Plus and the result was a mess of pages out there. Most businesses ended up with duplicate pages. This was a mistake Google made (in our opinion) but they're actually there to help get this cleaned up, so that's good.
The first thing to do is get a list of all your Google Plus pages. Do a search for your company name + "Google Plus" and you should be able to find them all.
I like to open a text document for stuff like this. Do that and then copy and paste all the URLs into that document. You should start to see different account numbers in the URLs.
An account number will look something like this:
https://plus.google.com/b/[YOUR ACCOUNT NUMBER]/dashboard/overview
where [YOUR ACCOUNT NUMBER] is the account number (what's between the slashes).
Look at each listing and decide which listing is best - meaning, the one that best reflects your business. It'll be the one with the right address on it. If you do have reviews on a listing, then you'll actually want to choose that one and then you'll get to change the address later (hopefully the reviews are good!).
Next, login to Google with your company account. Hopefully you have one. If not, then create one that's just for your company. You'll then need to go to each listing (logged in as that account) and try to claim each listing. There's a link on the page to claim it.
Then go to:
This is where you'll see all the pages/accounts you are able to manage.
If you have more than one listing shown for your company, you should see this message at the top:
"We're not showing this page because it's a duplicate of another. Learn more"
Click on Learn more
You should then be taken to Google help pages.
At the upper right, you'll see some links to get support and contact Google. Click that and you'll see instructions on how to have Google call you. Follow those instructions and someone from Google will call you and help you through the rest of the process.
Getting Google to help you is the best way to get through this. It's kind of their mess, so they'll help you through this.