Answer: Inform Sergio so he can sue the seller.
Explanation: when a fraudulent seller causes Hilda not to be given commission she earned from her last transaction, the best course of action is to let her broker, Sergio know of the fraudulent seller so he can be sued to court.
Sellers are required by law to make accurate disclosures regarding properties they sell. Failing that, they can be sued for fraud, this helps entitle the broker bringing a suit in civil law against the fraudulent seller to attorney’s fees and punitive damages.