You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

USER: David Gonzalez here. I have extended my leave, so I want to reschedule my itinerary dates.

ASSISTANT: Ok, I can help you with that. Please wait for a while.

USER: Sure.

ASSISTANT: David Gonzalez, there is no reservation found active under your name to do modifications in that.

USER: No problem, thank you for checking.

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