BMW Disappointed client

I’m very much disappointed with the service I got from BMW Bloemfontein. I took my car in for service on Thursday. It was an oil service. Yet when I received it showed that I had 4000KM until next service. So it was set for only 4000KM . On Friday morning when I switched it on, it started shaking and could not release any power. So I forced to drive it and it cooled down after an hour. On Saturday evening it was the same story. Then suddenly on Sunday it went on drive train mode. The notification disappeared after an hour. Everytime I start my car, it shakes and vibrates and doesn’t release any power. This is after I took it in for service and I’m told I can only take it in tomorrow for a diagnosis which I’m probably going to have to pay for. I don’t know if my car was tampered with during service or not but I’m truly not satisfied with whoever worked on my car because before I took it in for service, it never did this. And this is inconveniencing me. I can’t work comfortably or drive comfortable when coming to work. When I’m at work all I do is worry and can’t even leave to run my errands because then car will loose power whilst I’m driving.