tranny Slip

I was off to work hit about 30 mph and suddenly the transmission slipped.i can right back, but i turned around and went home .The shop I brought it to wasn't sure if it was electrical or not .Should I just bring it to a transmission shop?My concern is that every time I seem to have a car checked at a transmission shop they claim a new transmission is needed. Help needed . thanks

correction, the transmission came right back

is the car throwing any codes? Take it to the tanny shop and get them to diagnose it for free.