this is a common problem,stupid design

the lower control arm attach to the chassis via two horizontally acting rubber bushes that take the weight of the car.there is no supporting metalwork to help the rubber

fyi its normally the rear one that wears first,and the suspension geometry goes bad.one bolt is obscured by the gearbox,and this could be why your labour charge is so high.normally this bolt is cut off and the replacement is put in upside down.if the nut comes off,the bolt drops out and your wheel hits the bodywork

refit using thread locking compound

oh,use genuine ford arms too...they last the longest.