Retaliation in the Workplace

Who else can we report to when HR department is retaliating and the company executives are too scared to confront HR?

How do you suggest we, as compliance officers, set and enforce expectations for our "compliance partners" who aid in the investigation process? What is the most effective way(s) to communicate with them throughout this process?

Any suggestions/guidance on best practices in responding to callers while balancing the confidentiality of the investigation process?

What are the key data points for monitoring and measuring retaliation?