You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you today?

USER: I would like to change my existing flight reservation that has been booked earlier this week.Could you please help me in re-modifying my dates in the reservation?

ASSISTANT: Sure, may I know your name for modifications in your journey?

USER: Myself Joseph Brown.

ASSISTANT: Please stay online, let me check with your details.

USER: Ok, take your time.

ASSISTANT: Thank you for waiting. Sorry, there are no active reservations on your given name to change.

USER: It's ok, thank you for your help.

ASSISTANT: Thank you for reaching our service.