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 report a scam by an online marketplace seller, use this factual base: include the product or service, order number, dates, price, fault, prior contact, and supporting record.
Correct the record precisely
Correct only what you can support, acknowledge any real impact, and propose a practical way to prevent repetition. Request a specific lawful remedy and give a reasonable response date before formal escalation. 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 exaggerate, threaten staff, publish private details, or demand compensation unrelated to the loss. Use payment, regulator, insurance, police, data protection, or legal channels for fraud, danger, or unresolved rights. Do not recruit an audience, publish private evidence, or turn a misunderstanding into a campaign about character.