Dear
I am writing this letter to inform you that (organisation name) is considering (dismissing/taking disciplinary action) against you. This action is being considered with regard to the following circumstances: (describe with relevant concise details, dates, etc.)
You are, therefore requested to attend a disciplinary hearing on (date and time) is to be held at (venue) with (names of hearing panel). If you wish, you may be accompanied by another work colleague or a trade union representative.
Sincerely