NHTSA Complaint #11563270 — 2015 GMC ACADIA

I have a 2015 Acadia Denali with 95000 miles. I am getting the "service side detection system" message whenever I start my car, and the blindspot lights, cross-traffic detection etc. do not function at all. A"nationwide" problem I was told. I was also told that it would cost $800+ to replace if/when the part was available. I am really frustrated with this and was wondering a) whether this malfunction is a part of a service recall (given it is apparently a "nationwide" problem); b) whether the $800 replacement cost is accurate given that the part appears to be available for under $200 online; and c) whether purchasing this part will even fix the problem given that other forum members have stated that once this issue comes up, it continues to malfunction, even after the part is replaced. Very disappointed right now, particularly since this issue has been recurring on a number of GMC vehicles for at least 5 years.