You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Gary Hill.

ASSISTANT: How can I assist you?

USER: Due to change in my plans to visit Dallas, I would like to change my existing reservation. Can you help me with this?

ASSISTANT: Ok, I will help you with that.

USER: Thank you.

ASSISTANT: Sorry, I did not found your reservation in our sheet.

USER: Ok, not an issue. Thank you for providing information.

ASSISTANT: Thank you for connecting with our agency.