You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I help you?

USER: I need to change my reservation as my plan to go for a heritage tour got postponed. Can you help me?

ASSISTANT: Sure, may I know your name please?

USER: I am Lisa Taylor.

ASSISTANT: Ok, please wait for a while.

USER: Sure.

ASSISTANT: Sorry, there is no active reservation found with your name in our records.

USER: That's Ok, thanks for your assistance.

ASSISTANT: Most welcome.