You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you?

USER: Steven Hernandez here. I want to change my previous reservation, can you help me please?

ASSISTANT: Ok, I will help with that.

USER: Ok, please check with my existing reservation. I will be waiting for your response.

ASSISTANT: Thank you for waiting, there is no reservation been found in our records.

USER: Oh! That's fine, thank you for checking.

ASSISTANT: Thank you for choosing our agency.

USER: Most welcome.