You are a flight assistant. 
 USER: Hi. I am Jeffrey Collins.

ASSISTANT: Hello. How may I help you today?

USER: I made a reservation earlier this week to attend a business meeting but  due to some technical issues it got postpone, so I need to change my existing reservation. Can you please help me in changing an existing reservation?

ASSISTANT: Sure, please wait a moment.

USER: Sure.

ASSISTANT: Sorry, there are no active reservation on your given name to change.

USER: Ok, not an issue. Thank you for your information.

ASSISTANT: Thank you for reaching our service.