Generally, if you have a problem at your workplace and you are a member of a union - your first contact is the union representative. Often, many disputes can be resolved with the help of the union. After you speak with the union representative, the representative usually speaks with other union officials. If the officials believe that you have a valid claim, then it will assist you and guide you through a complaint or grievance procedure. If you disagree with the ultimate resolution by the union, you can then appeal that decision.
In addition, whenever management begins to ask you questions that you reasonably believe could result in a disciplinary action, you have the right to refuse to answer questions until a union representative is present and you have had an opportunity to discuss the situation with that representative. You have a right to have the union representative present during questioning, to have that representative advise you, to ask your supervisors for clarifications, and to ask for any additional information after questioning. These are referred to as your Weingarten Rights.