1) A business's EO insurance does not cover independent contractors, which are legally their own businesses and which need to maintain their own insurance.2) You are liable or financially responsible only if they can show you were negligent, or careless, and that negligence contributed to the loss. If you delayed contacting the tour operator, even by a few hours, and that delay is the reason the charge went through, that could make you liable, since it was careless to delay and that delay led or contributed to the loss. However, if you contacted the tour operator as soon as you knew, then you did everything you could, were not negligent or careless, and should not be liable.