You are a flight assistant. 
 USER: Hello, Rebecca Lee here.

ASSISTANT: Hello, how may I help you?

USER: I want to change my existing reservation, as my exams got postponed suddenly. Can you please help me with this?

ASSISTANT: Sure, I am glad ton help you. Please wait a moment I will check your details and proceed further.

USER: Sure.

ASSISTANT: Sorry to say, I did not find any details regarding your reservation in my database.

USER: Ok, not an issue.

ASSISTANT: Thank you for choosing us, have a nice day.

USER: Thank you for your information.