In the past it was not possible to change the name of a facebook page (and by page we mean a page set up for a company, product etc) at all, you were basically stuck with the name you used when you first created the page.
However, recently it has become possible to change your facebook page name.
What you need to do is to go to your facebook admin panel and select Edit Page and Update Info. In this section you will see a section for username and for name. The username is the URL that you have assigned to the page (this requires 100 likes before you are able to assign a URL to your page). The name is the title of the facebook page that you have created.
If you click on ‘Request Change’ next to the name of your page then you will be asked to fill out a form so that facebook can process the name change. You have to choose from 3 categories, for example if your company has changed name or if the original name was spelled incorrectly.
Once this form is submitted facebook advise that they will get back to you in 3 days about the change. If you attach supporting documentation regarding the change then the change of name may be processed more quickly.