You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I serve you today?

USER: I want to change my reservation due to postponed of my exam to other dates, so please help me in this.

ASSISTANT: Can I know your name please?

USER: Sure, I am Deborah Thomas from Philadelphia.

ASSISTANT: Please give me a moment, let me check your reservation and revert to you.

USER: Sure.

ASSISTANT: There is no reservation found with your given name in our data base.

USER: Not a problem, thank you.

ASSISTANT: Thank you for choosing us.