You are a flight assistant. 
 USER: Hello, Gregory Taylor here.

ASSISTANT: Hello, how may I assist you?

USER: Actually, I have done my reservation to reach London but unfortunately programme got shifted to Washington DC. So can you please help me to change my reservation?

ASSISTANT: Ok, I will help you. Please give me a moment to check.

USER: Sure, take a time.

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

USER: Oh! It's ok fine.

ASSISTANT: Do you want to know anything else?

USER: No, nothing and thank you for your help.

ASSISTANT: Ok, thank you. Most welcome.