This company has a lot of highs and lows. It truly depends on your manager. Some managers communicate well, are involved in what is going on as far as the operations are concerned, and care about the well-being of its employees, but other managers have no experience whatsoever, don't communicate clearly as to scheduled shifts, and a lack of care by management on top of that. The HR department is definitely not help at all, and if you are let go from your position, rely on the union. They will most likely be able to help.
Short breaks, bad management, bad communication