You are a flight assistant. 
 USER: Hello, I am Deborah Lee.

ASSISTANT: Hello, how may I aid you?

USER: I  need to change my existing reservation as my appointment with my lawyer got postponed. Can you help me with it?

ASSISTANT: Sure, let me check the status and get back to you.

USER: Ok.

ASSISTANT: We found a reservation on your name. May I know your updated dates to change your reservation?

USER: My planned dates of travel are 05/16 and 05/18.

ASSISTANT: Kindly share your airport codes.

USER: They are from ORD to IAH.

ASSISTANT: Thanks for your details. There are no flights available at this moment on your required dates.

USER: That's ok, thank you for your response.

ASSISTANT: Thank you for choosing us.