Maybe you should all write your suggestions for improvements. Even if you post them here (and not send them directly to your managers), we know that top management is reading you, so why not use the advantage of anonymous education of your managers?
You will not be exposed, and they will not feel too proud to "be taught" how to improve things. I am sure that they have difficulties to determine where to begin with changes and since unions are forbidden, they don't have your feedback. I think it is a good idea to provide them some suggestions, not only complaints (through surveys).
Dragana