IB phone agents are notorious for just straight up making up whatever story will get you off the phone. Aside from IT, probably the worst part about IB. Unfortunately without status it's basically HUACA until you get someone competent. You are also working with two strikes against you as I assume you're dealing in English (not always their strongest suit) and on the non-status line. I can generally get competent people in Spanish on the IB Oro line, but no guarantees.

IB can absolutely change tickets on BA metal to a different one. The sad reality is you have to call in knowing more than they do and what they can and can't do and when they refuse ask to speak to the supervisor.