You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Jessica Lopez here.

ASSISTANT: How can I assist you today?

USER: Due to the health issue, I want to change my recent reservation.

ASSISTANT: Ok, I will help you with that. Sorry Lopez, your name is not there in reservation list to change it.

USER: That's ok. Thank you for your help.

ASSISTANT: Most welcome. Thank you for choosing us. Have a good day.