The customer authorized the charge and was charged the correct amount. This claim does not meet one of the definitions of an EFT error in 1005.11(a) and you can deny a claim on that basis
VISA/MC may provide a chargeback right using the "Not as described" chargeback reason, but prior to exercising this right, the customer must make an attempt to resolve the dispute directly with the merchant and provide (to your satisfaction) sufficient documentation to demonstrate that the merchant did not provide the services advertised. The customer must provide you with a dispute letter that outlines their efforts to resolve with the merchant and the merchant's response.
This could any pictures the customer took of the accommodations compared to the website, a description of what was promised vs. what was delivered, etc.
At first glance, this sounds like a case of buyer's remorse for which neither Reg E nor V/MC provide any protections. I would want very solid documentation before attempting a chargeback. Rather than spending the $$$ on a chargeback, it may also be worth dropping a dime to call the merchant directly to get their side of the story prior to filing.
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