Pmb dealership ... personally dont trust them anymore

I no longer trust pmb dearlership. My car showed "engine fault" upon there diagnosis i was told i need to buy Actuator (R21000) & Clutch kit (R6000) and labour fees was +R10k. These parts were burnt and the only way to fix my car was to replace the parts. I called in another mechanic who said i need a new battery. And yes my car is up and running. Why is it that they cud not tell me that a battery change wud have sorted my car issues. Should i have got the loan and paid wat or were was my money going to go.... i no longer trust this pmb dealership....