2025 GMC Acadia OnStar Module

I purchased a 2025 GMC Acadia recently. One of the main reasons for purchasing was the Super Cruise feature. After signing all the paperwork, we tried to setup Onstar and found it not working. The dealership tried to troubleshoot but wasn't able to repair. I live 2 hrs away from the dealer and had to leave. When I got home I set up an appt at my local dealer, only for them to tell me the part is on national backorder and didn't even look at the car. I made another appt for April 14th but I'm starting to lose hope in this situation. Is there anyone who can help expedite this? No one should ever be able to purchase a new or slight used vehicle that isn't ready to go to work. The delaer who sold me the car told me all about their 182 point inspection, only to find out they missed the onstar not working.