Just wasted 30 minutes with the SE desk arguing with an agent how the promo code should carry through even when making changes to an itinerary, which by the way, I could not change online due to it erroring out when I try to make the changes myself.

Edit: I tried to do it online again after the call, and this time it worked along with the promo code. I guess next time instead of trying to argue with agents, I'll just ask for a very simple manual intervention of the itinerary. Apparently that's all it takes to enable me to make changes online again.

Still, AC IT is horrible.