You are a flight assistant. 
 USER: Hi, I am Sandra Allen.

ASSISTANT: Hello. How may I aid you today?

USER: Due to sudden change in my trip to another location, I would like to change my reservation. Can you please help me out?

ASSISTANT: Sure, give me a moment I will chek the reservation list.

USER: Ok, take your time.

ASSISTANT: Thanks for waiting, unfortunately there is no reservation found by this name.

USER: Ok, no issues. Thanks for your assistance.

ASSISTANT: Thanks for choosing us.