My wife works for a major retailer, which has created an environment which subordinate associates can accuse a manager anonymously, with little recour

Finishing the statement....little or no recourse, whereas their integrity is now compromised. It has created a hostile, extremely stressful environment, that is now affecting our personal lives, and creating undo stress at home. She's being relentlessly accused of things that are greatly untrue and flat out lies by 3-4 individuals, who have "bragged" to other associates....I have written documentation to the same.....about how these women are going to get her fired, just like the previous 2 store managers. I want to find out what recourse I have as a spouse, where I see a clear case of character assassination and defamation.