bakkie gearbox

I took my bakkie to them cause was stuck in 3 rd gear . he charged me 3500 to repair the gearbox. When i got it back by the second day it got stuck in second gear. I took it back he charged me again 1200 To repair the gearbox . when I got it back a week later it jumps out of 5 th gear and makes a loud noice when you put it bsck to second gear. This morning when i went back. Martiens the owner was arrogant asking what must he do about it. So i just left.