Final answer:
The first action when a customer complains about a foodborne illness is to investigate the complaint and gather relevant information.
Step-by-step explanation:
When a customer complains about a foodborne illness, the first action you should take is to investigate the complaint and gather all relevant information. This includes obtaining details about the customer's symptoms, when and where they ate the food, and any other potential factors that could be related to the illness.
It is essential to take the complaint seriously and report it to the appropriate authorities, such as the local health department, so that they can conduct a thorough investigation.