PROTEC BOSCH FAIL TO SERVICE CAR TO SPEC AND WANT TO RUN AWAY FROM COST AFTER VECHILE BREAKSDOWN DUE TO INCORRECT SERVICE DONE

Bosch at Protec auto basically serviced my M3 and put the incorrect oil into the car, imagine in a high performance car, they then send out a forensic specialist whom writes a report with no proof behind it. My words to bosch are the below: When I drafted my letter I provided proof from BMW in writing of the correct oil 10W60 to be used this report only states BMW said so, there is no proof, furthermore 10w60 is readily available at most spare shops or BMW itself how could it not be available at time of service, I do not accept this report as being valid and hold bosch liable for repairs the bearing was not lubricated correctly because the incorrect oil 5w40 was used which is also thinner if the car stay in the motor 10W60 why change the correct spec . Also Johanna and Cornelia can confirm your system was updated incorrectly as to the oil 5w40 that was used , they confirmed same when I was there to discuss the matter. I will not accept expenses for your incorrect work done on my vehicle. Bosch is liable for all the damages I check with other RMI centres as well and the listing the have for from BMW on their system is 10W60, why is it only protec Bosch system incorrect with 5w40.