Dynamic converters dont work all the time

I have bought stuff from them for 10yrs. They have built me 6 an a tranny. I have sent them over thousands of dollars of work, but not anymore. Got a new one summer didnt work, sent it back after 4 runs, an bearings were out.
I was told since I wanted the stall changed the problem was mine.

$750 rebuild this summer
$355 my problem bearings went out
____
$1105 bad mouth them for life