It helps when lodging a complaint to begin by saying something gracious, or expressing gratitude towards the person with whom you are communicating. Thanks for taking the time to listen. Thanks for your excellent work over the years. This increases the chance your complaint will be received.
The language in a complaint should be concrete and specific. Emotional judgments, character assassination, none of these things are likely to win you an ally to achieve your objective. Say what the problem is in three sentences or less.
Contributor: Adam Cole, A Jazz Musician Who Writes Books at acole