[Your name and correspondence address]
[Date]
[Recipient name, organisation and address]

Subject: Feedback about [service/interaction] — [reference]

Dear [name or team],

I am writing about my experience of [service or interaction] on [date].

The relevant facts are [brief chronological account]. I previously contacted [person or team] on [date], and the response was [summary, if applicable].

This affected me by [explain the practical effect without unnecessary personal detail].

I would appreciate [the clarification, response or improvement you are requesting]. Please let me know the appropriate process if this needs to be considered by a different team.

I have included [relevant evidence, if any]. Please confirm receipt and advise me of the next step.

Yours sincerely,
[Your name]