No matter how common or simple your business might be, you should seek a legal counsel because ignorantia juris non excusat (ignorance of a law is no excuse) both in regards to state and federal law.
Whether you are starting new business venture or negotiations, or your existing contract agreement has been violated, a help of a legal professional can save you stress, and help avoid costly mistakes.

1. Double check your facts. Re-read carefully your contract. Mark items that have been breached.
2. Contact the offending party. Try to resolve the dispute directly with them.
3. If it does not work, seek legal counsel.

Definition of due diligence:
1. law : the care that a reasonable person exercises to avoid harm to other persons or their property
failed to exercise due diligence in trying to prevent the accident
2. business : research and analysis of a company or organization done in preparation for a business transaction (such as a corporate merger or purchase of securities)