Darren and sons Bmw bad service

Took car for valve stem seals repair, car was driving fine only smoking after idling , Darren quoted 16 k to repair after a week he demands more money for part that were fine. I paid about 20k got the car back and he failed to do the timing correct car misfired and engine bay had smoke coming out . Got car towed to a different garage They found out tappet cover gasket leaking engine cover bolts missing and few broken plastic parts. Timing was off and he blames chain tensionsers which he changed,when they checked the parts all were old parts. He failed to fix the car as it misfired and blamed air flow meter . He kept blaming different car components . Darren and Sons don’t know Bmw don’t take your car to him . He is useless