If you have reason to believe that a meeting with your administrator will result in discipline, you have the right to have a union representative at that meeting. You must request to have your representative present because your administrator doesn't have to inform you of that right.
If your administrator insists you meet without a representative, you must attend that meeting, but do not have to answer any questions. You cannot legally be disciplined for refusing to answer questions when you requested a union representative (UniServ) but were not allowed one. In such an instance, it is best to put your request in writing.
"If this discussion could in any way lead to my being disciplined or terminated, or affect my personal working conditions, I respectfully request that my Association representative be present at the meeting."