Car service

I have been bringing my car to this dealership since 2017 and have always received really great service. I dropped my car of bright and early today for a service, I get a call to come pick it up only to be given back a car that still clearly has the service light and other lights on.

I enquire on why the lights are still on if my car is fully serviced and I’m told they “forgot to diagnose the car”. This is just after 5pm. So why has my car been here all day?

The car is clearly noting “check abs, check esc, check hill start assist etc”… so what’s there to diagnose? The service light is also still on. Why don’t we start there or is it because I haven’t paid a diagnostic fee?