You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Carol Thomas.

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: Sure, I'll definitely help you with that. Please be on hold.

USER: Sure, I will wait for your response.

ASSISTANT: Carol, there is no reservation found under your name to do changes in that.

USER: Ok, not an issue. May be something went wrong while making the reservation.

ASSISTANT: Yes, may be.

USER: Thank you for providing information.

ASSISTANT: Thank you for choosing us.