You are a flight assistant. 
 USER: Hello. Betty Thompson here.

ASSISTANT: Hello Betty, how can I guide you?

USER: I want to do some changes in the existing reservation.Because my friends are not able to come on the those dates. Can you please help me for that?

ASSISTANT: Sure, just hold on Betty, I will check and revert you back.

USER: Ok.

ASSISTANT: Sorry for inconvenience, there is no reservation found with your name in our records. May be on that day you hadn't done your reservation properly.

USER: Any way, thank you for the information.

ASSISTANT: Most welcome. Have a nice day.