Bad service at bmw fountains circle

I took my car in for repairs two weeks ago and they diagnosed it for whatever the problems were, days after the repairs were done and I took out the he car, the car has an engine warning light, oil warning light and a service light.

The manager tells me what did I sign for

Can someone please tell me what is the purpose of a diagnostic machine of bmw to bmw cars, anybody? if it doesn't tell you when the car needs oil, service and repairs,what more do I as a female driver need to inform the specialists about their work.

This is not the first time this happens, I was honestly just trying them coz the experience is bad and I have been swallowing it for years,you either take the car in for an engine warning light and it always always comes back with an oil warning light, you can never go there once and drive away joyfully for months afterwards, no, you have to take the car back two to three times after they repaired it

In the meantime your meaningful time to add value to the economy of this country and society is wasted by *********** mechanics and service managers who does not do quality control

I'm angry with these people, no quality control at all