your address
date
date
name or title (of recipient)
business address
Dear Sir or Madam (or name):
(Optional, especially if writing to a named person) ask for the person's help, eg "I'd really appreciate your help with this."
State facts of situation, including dates, names, reference numbers, but keep this very concise and brief .
State your suggested solution. If the situation and solution is complex, state also that you'll be as flexible as you can to come to an agreed way forward.
(Optional, and normally worth including) state some positive things about your normal experience with the organization concerned, for example: that you have no wish to go elsewhere and hope that a solution can be found; compliment any of their people who have given good service; compliment their products and say that normally you are very happy with things.
State that you look forward to hearing from them soon and that you appreciate their help.
Yours faithfully, (if not sent to a named person) or sincerely (if sent to a named person)
Your signature
Your printed name (and title/position if applicable)