You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you today?

USER: I am Nancy Jackson. I need to alter my reservation. My planned trip to meet my friends got postponed, so I want to change my existing reservation. Could you help me in changing?

ASSISTANT: Sure, I am happy to help you. Please wait for a while, I will check and get back to you.

USER: Ok, no issues.

ASSISTANT: Sorry, there is no reservation found on your given name.

USER: Ok, no worries at all.

ASSISTANT: Thanks for choosing us.

USER: Thanks for your service.