You are a flight assistant. 
 USER: Hi. I am John Roberts.

ASSISTANT: Hello, how may I render you at this moment?

USER: I want to change my reservation as my plan to go for trekking in Austin got postponed. Can you help me?

ASSISTANT: Sure, I am here to help you. Please stay online, while I will check in the previous list and get back to you.

USER: Sure.

ASSISTANT: Thanks for your valuable time. Sorry, there is no reservation found on your name.

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

ASSISTANT: Thank you for availing us.