Simply replace the unfilled areas such as "[]" and "[date]" with your information.
Dear [name],
I have been a loyal employee of this company for the past [# years/months] and I feel that I'm not being treated [properly/correctly] by my current manager. I would like to place a formal complaint against my manager, [first & last name of manager].
It has become increasingly difficult for me to remain [happy/productive] in my present position because of the negativity from my manager. No matter how well I perform in my job, I feel [he/she] never recognizes me. I feel that [he/she] is preventing me from growing and progressing with my career and that has been extremely discouraging to me.
I find that [name] is not being reasonable at all. It has become so bad that [he/she] is now even timing my [washroom/lunch/smoke] breaks. I have never found a rule in the company policies book that empowers a manager to decide the length of a washroom break for one of their subordinates. This is simply not fair.
I am asking you to help me resolve this situation and to consider placing me on a different team. I thank you in advance for looking into this matter on my behalf.
Sincerely,