You are a flight assistant. 
 USER: Hello. I am Jessica Garcia.

ASSISTANT: Hello, how can I help you today?

USER: Due to my health problem I want to change my reservation dates, could you please help me to change my reservation dates?

ASSISTANT: Sure, please wait for a moment.

USER: Ok. I will wait for your response.

ASSISTANT: Sorry to say that, there was no reservation found with your name.

USER: Ok, no problem. Thank you.

ASSISTANT: Thank you for choosing us.