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 apologize for ignoring a host's local customs, use this factual base: confirm the booking, timing, guest, transport, or budget change and who now has to adjust.
Resolve the next dependency
State what is complete, what remains disputed, and which action would move the situation forward. Offer a replacement plan, reimbursement, or clear decision before the next real deadline. Make the immediate next step clear enough that the recipient can answer without reconstructing the entire history.
Document without threatening
Do not minimize lost money or time, and do not invite extra people into a plan without consent. Follow venue, transport, insurance, and local safety rules when an emergency or stranded traveler is involved. Keep a factual record and describe only remedies you are entitled and prepared to use.