What you are attempting to do is change the "gateway" city on your booking. If the promotion that you booked under was some kind of regional promotion or something similar, changing the gateway city could affect the fare pricing. That's why the TA has to make the change since it could potentially involve money.
I saw the new bar menu on Facebook. Here's the "new" Chairman of the Board recipe: Grey Goose Vodka St. George Terroir gin Cointreau The Bitter Truth bitters I'll be ordering the "classic" Chairman of the Board as described by Thrak...