1. OP has gone way overboard about something which is self-evidently an accounting error.

2. Send an email to the property. Given them 5 days to write back and advise of a credit. Make the email short, no ranting about "furious" and "fraud".

3. If you don't get a positive response, do an online dispute with Amex. Chances are this falls way below Hilton's threshold for researching and will simply be granted.

4. Don't bother writing to the CEO. Complaints go to the ordinary CS database, they just get a response saying that the CEO asked the writer to "personally" handle the matter through the "executive office". The same people who handle Santa Claus and the tooth fairy.