Brake Disc Caliper problems of the 2018 Infiniti QX60

I previously leased the qx50 and had no issues with that vehicle. We traded it in for more room and upgraded to the Qx60. Brakes began squealing intermittently 6 months after leasing (leased brand new in June 2018) and took it to the dealership we leased it from. The squeal occurs when driving in reverse during application of the brakes. (my husband believes its an issue with the calipers. ) we were told that there was nothing wrong with the brakes. At the second service department (serviced in July 2019 since the squealing has gotten much worse) I was handed a "service bulletin" saying that the noise is normal, and no service action is necessary (see attached bulletin for more details). I contacted the Infiniti consumer affairs group and filed a complaint. I was told today (7/26/19) that there was no course for vehicle replacement or repairs and there was nothing they could do at this time. I have done my research on Infiniti vehicles and there are repeated issues with brakes on different makes and models. One was a severe accident in 2012 where the brakes faltered on a qx56 and 3 family members were killed. Infiniti was held liable and paid $25m. Another more recent class action lawsuit (2016) has been filed on the qs50 by an individual in California, that claims he has had numerous brake issues (see case no. 2:16-cv-07378) with no resolution with Infiniti. In this particular claim, it sites a 2014 litigation over defective brakes that were causing brake failure in multiple models. No other details were available on the 2014 litigation. What can the NHTSA do to either take Infiniti off of american roads until the issue is resolved or take serious action against Infiniti to force them to provide their drivers with safe braking systems?.