You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello,.

USER: I am Nicholas Roberts.

ASSISTANT: How can I render you today?

USER: I need to change my existing reservation, as my exam got postponed. Please help me in changing?

ASSISTANT: Sure, we are here to aid you. Please, wait for a while I will check with the reservation and let you know.

USER: Ok.

ASSISTANT: Thanks for your valuable time. There is no reservation found on your name Nicholas Roberts.

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

ASSISTANT: Thank you for reaching us.