For AC Reservations:
"A service fee applies for initial bookings or processing changes that could have otherwise been completed online. The service fee is $20 CAD ($15 USD) per passenger, with a maximum fee per booking of $50 CAD ($37 USD)."
Sorry, I have no idea what date this took effect.
Given the statement above from AC's website, I believe we should all demand refunds for those times we've been forced to pay the fee when trying to book a certain fare class. I'll certainly mention the statement next time booking international H or U class.