2027 GMC Yukon

Within the first 100 miles of driving my new 2027 GMC Yukon Denali Ultimate, its OnStar system stopped functioning. I returned the vehicle to an authorized GMC dealership on XXX, five days after purchase and delivery. The dealership advised that an electronic module must be replaced, but that the replacement part is on backorder with no estimated availability or repair date. The SUV remains at the dealership with approximately 200 miles on the odometer. I am concerned that the OnStar failure may affect emergency SOS assistance and Automatic Crash Response. GM has not provided written confirmation identifying which emergency and driver-assistance functions remain operational. The dealership has not declared the vehicle mechanically undrivable, but I do not consider it suitable for my personal use until these emergency functions are confirmed operational or repaired. I request NHTSA review this reported failure as a possible safety-related defect. I opened a case with GM - Case #XXX. I also sent a notice to GM management on XXX detailing the issue and specific requests I am making. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT(FOIA), 5 U.S.C. 552(B)(6)