I believe that most CSO's work as one or two per department and do not have a dedicated supervisor to help them. You have to find the supervisor that you trust, or believe has the capability to handle the situation, and approach them about the problem.
I would try to be low key about it as well. Please don't wait until you can't stand it any more. (I have done that and I can tell you it can cause more problems for you than the original complaint.)
And don't get your hopes up too high in case little changes.