I need a train departing from Cambridge. 
Ok, where will you be going?
I will be going to London Liverpool Street on Sunday. 
And what time would you like to leave after or arrive by on saturday?
I'm leaving on sunday, not saturday. Can you make sure that's correct? And I want to arrive by 21:00
I am so sorry about the mix-up in days. I have TR0189 arriving Sunday at london liverpool street at 17:27. Would this be acceptable?
thanks so much, thats all i needed
Well, I'm glad I could help. Have a safe trip. Goodbye.