You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am Debra Clark.

ASSISTANT: How can I assist you Clark?

USER: Due to change in my trip, I want to change my existing reservation.

ASSISTANT: Ok. Please wait a moment, Clark. Clark, there is no active reservation found with your details.

USER: Thank you for your time. No issues.

ASSISTANT: Thank you for reaching us.