Small Biz Trends has a solid explanation on how to merge your former Places Page (for Google maps) with your "Google+ Business Page."
It's very easy, the Business Page you created simply click the "Verify Now" button towards the top. You'll want to make sure the information on the page is complete.
Google will re-verify your business by Postcard.
Small Business Trends: How To Merge Your Google+ Local and Business Pages
If you have multiple Google accounts, Coolhead Tech can help migrate your email and accounts to one Google Apps for Business Account.