Insurance is regulated on a state by state basis, not at the federal level. This means that there is no single agency responsible for monitoring how life insurance is provided and no single organization responsible for ensuring that the rules and laws are being followed.
In most states, the agency you need to contact is called the state insurance department, but the name may vary from one state to another. For example, some states have a state insurance commission, and others include insurance monitoring and regulation in the state's Department of Commerce. Without knowing which state you reside in, there is no way advising you of the exact name of the agency you will need to contact.
You can find out what the name of the organization is in your state by using a search engine such as Yahoo or Google, and typing the name of the state you live in, followed by the phrase "insurance department," and pressing ENTER. This will provide you with a list of organizations related to insurance, beginning with your state and then expanding to other states farther down the search results. To refine the search so that it only displays government offices, append "site: .gov" (without the quotation marks) to the end of your of your search query. This trick will work in Google but may not work with other search engines, such as Yahoo or Bing.
Alternatively, you can use a website which provides the information for all states in a single location. A good source for information of this type is the National Association of Insurance Commissioners, or NAIC. This organization provides many types of insurance information as well as a page dedicated to the names and contact information of the insurance departments for all of the United States. The page for that information is available at //www.naic.org/state_web_map.htm, and can be accessed from any web browser.