You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I guide you today?

USER: I am Dorothy Lewis. Due to sudden changes in the dates of summit which was going to be held in that place.So I want to change my existing reservation. Could you please help me?

ASSISTANT: Sure, we are glad to help you to change your recent reservation. Please wait for a while.

USER: Ok.

ASSISTANT: Thanks for waiting, there was no reservation found on your specified name.

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

ASSISTANT: Thank you for contacting our service.