What is one valid reason for refusing a service request?

Refusing a service request because the device has been modified is a valid reason due to the potential complications that modifications can introduce. When a device is altered in any way, it may affect reliability, safety, or functionality. These modifications can also void warranties and complicate the service process, as technicians may be unable to determine if the modifications are causing the issue or if the original components are still functioning as intended. Therefore, servicing a modified device could lead to further issues or generate liabilities for the repair service. Recognizing this, many service policies include clauses against servicing modified devices to maintain standards and ensure safety for both the technician and the customer.

In contrast, the other options do not typically justify refusing a service request. A device that is new and under warranty is generally eligible for service, while being a repeat client is irrelevant regarding the validity of a service request. Additionally, if a device is covered under service, that indicates it should be eligible for repairs or replacements, not grounds for refusal.