I'm looking for a train that goes to Cambridge on Saturday
Would you like to leave or arrive by a certain time?
I would like to leave after 21:30.
Where will you be departing from?
I will be departing from broxbourne. 
We have 3 options that meet your criteria. All depart within an hour of each other starting at 21:32. Would you like me to book one of them for you?
Yes, whichever train has seats available for 7 people.
Your booking was successful, the total fee is 100.24 GBP payable at the station.  The train departs at 21:32. Your reference# is UZFW2TAQ. Is there anything else?
No that's all thanks 
Okay, have a good day then