You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I help you?

USER: As my plan to visit my grandmother's house got postponed I want to change my existing reservation, can you help me with it?

ASSISTANT: Sure, May I know your name to check the details of your reservation?

USER: Yes, you can call me as Jerry Brown.

ASSISTANT: Ok, please wait a moment.

USER: Sure.

ASSISTANT: Sorry Jerry, I didn't found any details regarding your reservation in my database.

USER: Ok, thank you for the information.

ASSISTANT: Thanks for choosing us. have a nice day!.