Transmission Not Go Into Gear problems of the 2016 Hyundai Sonata

The automatic transmission on the 2016 Hyundai Sonata hybrid went out on the car oct 31, 2019. My wife was driving the car, when she lost drivability of the car. The car would not go, she was able to park it on a side street. She restarted the car but would not go into gear, the engine was running. The car was towed to the closest dealership, when scanned, indicating of a transmission problem. The car has been at the dealership since oct 31, 2019 with no eta of when a new transmission will be available to repair the car. At this point I can not sale the car because it needs a transmission. Hyundai needs to give a date when the transmission will be available. The dealership has no time frame when they will get a transmission from Hyundai.

When I drive my Sonata, sometimes the gears do no switch. I can drive on a flat or inclined surface and it will act up. We've taken our car several times to the dealership for diagnostic testing to see what's going on. But when the car is connected or the serviceman drives the car, the car will switch gears and nothing is found on the diagnostic test. We currently driving a few states over and our car is not switching gears at times, affecting the gas mileage. My husband and I will decelerate until gears switch and then accelerate again.