I want to leave for Cambridge by train on Wednesday. 
Okay, where are you departing from?
I'll be coming from london kings cross
When do you want to leave London Kings Cross?
i will leave on wednesday
how about TR5725 that leaves at 05:17?
That will work. Will you please book it for 5 people?
It is booked and your reference number is EKDNFGB7. Is there anything else?
That is all I needed. Thanks!
You are more than welcome!