You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you?

USER: I would like to do some modifications in my existing reservation, can you aid me in that?

ASSISTANT: Ok, please can I know your name to check for your reservation in our records?

USER: Sure, the ticket has been reserved on the name Melissa Clark.

ASSISTANT: Thank you for waiting, sorry as per your request we can not change your reservation because there is no reservation found on your name.

USER: That's ok, no problem. May be my friend has been modified and I 'm not aware of it. Anyway, thank you for the information.

ASSISTANT: Ok, thank you for choosing our agency.