Make room for the other version
Ask what the other person understood before assuming that you are arguing about the same facts. For a message about how to ask a doctor for a second opinion, use this factual base: separate symptoms, diagnoses, medication, dates, and clinician advice from assumptions or internet research.
Correct the record precisely
Correct only what you can support, acknowledge any real impact, and propose a practical way to prevent repetition. Ask for the record, appointment, review, accommodation, or care decision through the correct channel. Make the immediate next step clear enough that the recipient can answer without reconstructing the entire history.
Agree on a testable next step
Do not share another person's medical information or treat a message as a substitute for clinical advice. Contact local emergency or urgent medical services for severe, worsening, or immediately dangerous symptoms. Do not recruit an audience, publish private evidence, or turn a misunderstanding into a campaign about character.