Clarify the agreement that existed
Identify the promise, policy, schedule, ownership, or shared understanding that applies before assigning blame. For a message about how to resolve an unpaid shared vacation cost, use this factual base: list the amount, date, reason, receipt, prior agreement, and any part that remains genuinely disputed.
Resolve the next dependency
State what is complete, what remains disputed, and which action would move the situation forward. Propose a payment, refund, evidence exchange, or installment plan with dates both sides can assess. Make the immediate next step clear enough that the recipient can answer without reconstructing the entire history.
Document without threatening
Do not threaten public exposure, add invented fees, or treat hardship as proof of dishonesty. Use secure payment methods and qualified banking, consumer, legal, or fraud support when appropriate. Keep a factual record and describe only remedies you are entitled and prepared to use.