Frustrations with engine failures on a car

The customer services department protects the dealerships over the customers, no fairness in resolving queries. I have had 2 engine failures on my 116 in less than a year and all these were reported to BMWSA customer services. My car went to AutoBavaria Midrand last year November to be fixed after i had reported idling issues to them for a long time and eventually an engine replacement was done sadly from that time i have not enjoyed my car it has been breaking down now in October the engine was replaced again. I am not getting clarity as to what is the main cause of this and if it can be fixed or not. The dealership instead insists that I buy a new car which is not in my favour, I feel so helpless and have no support from BMWSA.