Mito
In the spirit of trying to follow chanels, and this is depending on what the complaint is, I would suggest you follow Upstate's suggestions.
Nothing creates hard feelings that blasting off over the heads of local management, who would rather take care of local situations themselves if possible. While you might get the result you are looking for, you will create a relationship that will be strained at best.
Work within the system until the system does not work, then do what has to be done.
I guess it goes back to treating people like you would want to be treated. If I have done something against you, come to me first before you run all over the place complaining. That is the way I would want to be treated, and try to treat others the same way.
d