You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I assist you today?

USER: I want to change my reservation due to health problem, can you help me?

ASSISTANT: Sure, please mention your name.

USER: I am Sandra Garcia.

ASSISTANT: Please wait a moment, let me check with your details.

USER: Sure.

ASSISTANT: Sorry, there are no active reservations on your given name to change.

USER: No problem, thanks for checking.

ASSISTANT: Thank you for reaching our service.