Automatic Transmission Control Module problems of the 2011 Nissan Altima

2011 Nissan Altima sr sedan 3. 5 cvt. When driving, cvt goes into safe mode with reduced acceleration, indicating a transmission issue and would also trigger vehicle dynamic control system fault. . Original engine code was p0175. Had mechanic replace 31935-1xf00 speed sensor assy. Problem was not corrected. Took to local dealer and was told needs new transmission control module unit $850 and new transmission $3,500. Only 39,400 miles on vehicle (60,000 mile powertrain) but past he 60 month warranty by 5 months. Nissan will not cover. Nissan na consumer affairs contacted, researched and also denied. Will not cover and will not provide any partial assistance. Car is in excellent condition, driven lightly and no way transmission should need to be replaced at 39,000 miles. Manufacture date of vehicle is Dec 2010. Nissan extended cvt warranties to 10 years / 120k miles for several years because of the same and other cvt issues. Stopped extended warranty for 2011 models. Don't know if car is safe to drive or if transmission is going to fully fail. Took vehicle back from dealer, can't afford to fix. Now trying to replace transmission control unit with used same year/model. When vehicle is completely disconnected, trouble codes cleared and all electrical drained, then reconnected, all issues disappear for 10 to 20 miles of perfectly normal driving, then issues recur with cvt fail safe mode and vdc fault. Nissan should be recalling this issue and correcting it!! again don't know if vehicle is safe to drive or if transmission is going to fail in the middle of getting onto highway in heavy traffic? dealer diagnostic showed a number of codes: p0175 input speed sensor a (even though it has been replaced and new), p1700 cvt c/u funct, p1715 in puly speed, u1000 can comm circuit and also told the tcm is not sending a signal.