A3 definitely restricts actions that agents can take, I had a curious case of IRROPs in SKG where local A3 agent said he could not put me on a different flight due to my booking being "locked" somehow. It was due to weather, so by the time I reached phone support, seats on a flight I wanted were already gone.
I never had any issue asking A3 own agents to make any changes to my booking, so I have no reason to suspect that agent just wanted me to leave him alone with the rest of the pax from that cancelled flight.