Noises During Shifting problems of the 2016 Ford Mustang

Since I have purchased the car with 300 miles I had to take the vehicle in because the transmission was at times, hard to shift, would grind a gear. Locked me out of a gear, and in general can shake and produce loud thumping noises when engaging gears while sitting at a standstill or even while driving down the road. I was told at the time that this was normal behavior. I had test drove more than one car before purchasing this one. None of the others behaved this way. I have done more research and discovered that this is a very intermittent issue between builds of the transmission. I took it in again for service. They had removed the transmission and serviced some parts. Upon getting the car back it almost immediately went back to doing the same thing. This is not a big safety concern, but could cause bigger and more expensive issues down the road depending on what is happening to the transmission. This is one of four complaints I have with this particular vehicle that have not been resolved.