You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may aid you?

USER: Shirley Phillips here, please help me in making some changes in existing reservation, due to my busy schedule on my previously planned dates.

ASSISTANT: Sure, let me check the details of your previous reservation and revert you back.

USER: Ok.

ASSISTANT: Sorry Phillips, your previous reservation is not booked properly so it not found in our data base.

USER: No issues, thank you for clarification.

ASSISTANT: Sorry for inconvenience.

USER: Ok, no problem.

ASSISTANT: Thank your for contacting us.

USER: You are welcome.