You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: I am Ruth White. Due to some issues, I want to change my existing reservation. Can you please help me to change my reservation?

ASSISTANT: Sure, I will help you with this.

USER: Thank you. I will travel from DCA to SFO.

ASSISTANT: I have found your reservation, can you please provide me your travel dates?

USER: I am planning to travel on 07/23 and return back on 07/25.

ASSISTANT: Sorry there are no flights available on this route on your provided dates.

USER: Not an issue, thank you for the information.

ASSISTANT: Thank you for approaching us.