CLA 180 (YOM 2017) - battery draining issue since last service!
I kept the engine running for about 3 hours! And then I turned it off and try to start up after about 30 minutes the car won't start and the battery seems to be dead

People who did the service work said that they cleaned up the windshield washer tank and they had to remove the front bumper to get to it. However, by looking at how they tried to diagnose the battery issue, I got the feeling that these guys don't have a good sense of what they are doing. I'm taking the car back to the dealer tomorrow.
Any tips on where to look would be much appreciated as I can pass them to the mechanic doing the diagnosis.


