You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I assist you today?

USER: I want to reschedule my recent reservation as my plan for visiting the Downtown aquarium in Denver got postponed. Can you help me in changing the reservation made on name Helen Roberts?

ASSISTANT: Sure, I would be happy to help you. Please give me a minute to check.

USER: Sure, take your own time.

ASSISTANT: Thanks for being waiting, Sorry to inform you that there is no reservation found on your mentioned name.

USER: Ok, no issues.

ASSISTANT: Thanks for approaching us,.

USER: Thanks for your time.

ASSISTANT: Have a great day.