A service-related complaint refers to issues related to the services provided by the hotel or organization.
- Lack of assistance with luggage is a service-related complaint, as it pertains to the level of service provided to guests.
- Lack of public transportation is an external issue and is not related to the hotel or the services it directly provides.
- Lack of water in body is a health-related concern, not a service-related complaint.
- Bad weather is also an external factor that cannot be controlled by the hotel and does not fall under service-related complaints.
Thus, the correct answer is Lack of assistance with luggage.