Your co-worker did nothing wrong. She saw what she believed was dishonest conduct and reported it. Management acted on that information. Had she lied about something, you might have had a case but she didn't from what you describe. Even if you did, as others will tell you, these types of cases are a. expensive to litigate and b. take a long time. You gave a story that many dishonest employees give and they had probably heard before. Did you talk to the actual manager of the restaurant or just the manager on duty? If it was just an MOD, you could try appealing to the GM but don't hold your breath.

