transmission frozen but shifts in manuel?
 

tranny slipped 2x on a 2006 mazda 2.3 liter dual overhead cam. 130 k miles. 1 owner reg maintenanced. The engine seized, froze. Pulled over immediatly. 10 min later started up no issues. Tranny shop couldnt duplicate the issue and no gunk/ metal was in the fluids. They did not advise a new transmission. They mantenanced it new fluids. I dont think they "flushed" the fluids. Two days later in 5th gear over 80 mph on freeway it "stuck" rpm's were reving and it wasent shifting properly. Manually downshifted and parked it and bought a new car. It still runs and shifted fine in manuel. Called shop, they advised over the phone a new transmission. He seemed eager to buy it for $500.00 after he knew the car was replaced. Can i get a refurbished tranny with labor for less then 2100$ in nor cal? At first it was $3500 then they called back with a cheaper option of a refurbished for $2100 and sinse it easily shifted in manuel could i just drive it in manuel ...? IDK... Could it be something more minor? And even if it in fact needs a new tranny would i cause furthure damage if i drive it in manuel. Any info will help any thoughts at all thank you