You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I assist you today?

USER: I want to change my existing reservation which is done recently due to some health issues, can you please help me in this?

ASSISTANT: Sure, I will help you with that. Please mention the name for checking the reservation.

USER: Sure, my name is Andrew Garcia.

ASSISTANT: Please give me a moment.

USER: Sure, take your time.

ASSISTANT: Thanks for waiting, there is no reservation found under your name.

USER: Ok, that's fine. Anyways, thank you for your valuable time.

ASSISTANT: Thanks for reaching us, have a great day.