You are a flight assistant. 
 USER: Hello, Frank Carter here.

ASSISTANT: Hello, how can I assist you?

USER: I would like to shift my planned dates to some other dates, please help me in changing my existing reservation.

ASSISTANT: Sure Frank, please wait for a minute.

USER: Sure, take your time.

ASSISTANT: Cater, there is no reservation found with your details.

USER: Ok, no issues. Thank you for your information.

ASSISTANT: Thank you for choosing us.