transmission bangs when shifting gears

Bought the car used, everything OK for a week, then transmission slips, Ford reprogrammed the transmission, this stopped the slipping. Then transmission starts Banging on shifts ,but not all the time, worse while going around right corners. Ford rebuilds the transmission said everythings OK . Trans does same thing as I pull out of the dealership. Takes another year to get the company rep to answer dealers questions. Finally she said to change the valve body in the trans ,the only thing that hadn't been changed on the 1st rebuild. That was the answer!!!!!!!!! Ford did cover the repairs