Transmission Problems on 2006 Dodge Charger

Will my problem starts when i was doing around 160 km on the highway and then the car didn't change into 5th gear it just died as if its on neutral so i took the car to the nearest mechanic and he checked the transmission oil and found out that it has a leak so he buts new oil in it and fixes it and changes the filter but then the same problem happens but in 3rd gear so what should i do some people said but in a new software update but i don't now
Will you please help me

Asked by for the 2006 Dodge Charger
Im having problems with my 2006 Charger R/T. The transmission will not go into third gear sometimes. I took it to the shop and they told me that it was some sensor in the trans that went back.The fix costs almost $700. This is the second time I had to put out major money for this car, and it only have 43,000 miles on it. Word of advice get rid of the car and save yourself the trouble. The car looks nice but its not worth the head ace.
just had trans overhaul done on my 06 charger rt. trans was slipping out of gear low and hi speeds, usually 3rd or 5th gear. only 40k miles. had to replace torque converter. under warranty otherwise $3k job at dealer. think this is my last detroit car. no confidence .