Has anyone tried phoning LAN and changing dates on an already ticketed booking?

I've flown on one of these and the ticket agent did notice. Dialogue went something like this:

Agent- "Sir, I notice your ticket was issued under some chilean airline. Do you know why?"
Me - "I'm sorry I don't understand what you mean. The tickets were booked by my corporate travel department."
-"Well just that these tickets were issued under another airline stock than ourselves."
-"interesting. well i dont know, the travel department just book what I tell them to book."