You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: Melissa Garcia is here.

ASSISTANT: How can I help you today?

USER: I have planned for a holiday trip with my colleagues, unfortunately my trip has been postponed due to some health issues.So I would like to alter my existing reservation. Can you please aid me in changing?

ASSISTANT: Sure, I will help you with that, can I know your good name to proceed further?

USER: I already mentioned above.

ASSISTANT: Sorry, no reservation is found on your name in our database.

USER: Ok, no problem. Thank you for your information.

ASSISTANT: Thank you for reaching us.