You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I help you?

USER: I am Robert Walker.

ASSISTANT: Yes, Robert.

USER: Can you please change my existing reservation? because my sister reserved me a ticket with a wrong airport and location.

ASSISTANT: Sure, can you please be on hold while I'm going to check your reservation is existing or not in our database?

USER: Sure, I will be waiting.

ASSISTANT: Robert, there is no active reservation found under your name in our records to do modifications in that.

USER: No issue, thank you for your time in checking.

ASSISTANT: It's my pleasure to serve you. Thank you for consulting us.