Upper management don't care at all. I know of several employees that have complained about their direct managers, and it went unheard, the managers were notified as to who complained, and subtle retaliation was brought against the employee(s). The bullies of the company get promotions, while good hard workers go unnoticed and unappreciated. Managers push standard employees to do the work of 3 employees, supervisors and managers. We are not compensated for the extra work. We are not promoted for doing the extra work. We get, instead, a "we appreciate the hard work the TEAM has put forth". It wasn't the TEAM, it was 2-4 good hard workers while managers reap the reward.
I do not suggest complaining to the HR support page as they contact you to find out more about the complaint, but then do nothing about it. It's essentially just a ploy to make the company feel like they have answered your concern.