2000 Chrysler Grand Voyager NOT SURE

HAVING TROUBLE WITH MY TRANSMISSION. IT WAS FINE UNTIL I HAD A REAR MAIN SEAL FIXED.
FROM A OIL LEAK I HAD. NOW MY TRAINEE SLIPS AND WON'T CHANGE IN GEAR. I NEED TO KNOW PLEASE IF
THE GUY DID NOT PLACE BACK THE TRAINEE RIGHT, THAT WOULD COARSE THAT THANK YOU SO VERY MUCH.
"NEED YOUR HELP" SUSAN I WILL DONATE SOME MONEY WHEN I GET PAID FRI SO PLEASE WILL YOU HELP ME. MY VAN IS BACK IN THE SAME GARAGE, I JUST DON'T WANT HIM TO RIP ME OFF.