You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I guide you for today?

USER: I would like to change my travelling dates in my previous reservation due to my leaves got postponed. So please help me with changing my reservation.

ASSISTANT: Sure, I am here to assist you about changing your reservation.

USER: Thank you.

ASSISTANT: Can you please let me know your name to check the active reservation in our booking list?

USER: Sure, please check  my reservation with my name Mark Carter.

ASSISTANT: Ok, please wait while I will check the reservation status and will revert back to you.

USER: Sure, I will wait for your response.

ASSISTANT: I regret to say this Mark Carter, after check our booking list with your name I have not found any of the reservation with your name.

USER: Oh! May be it has not booked properly while booking. I will check my mail and contact you soon.

ASSISTANT: Sure, I am free to provide you assistance at any time.

USER: Anyway, thank you for your time.

ASSISTANT: You are welcome, thank you for choosing us. Hope you have a nice day ahead.

USER: Most welcome.