I received an email from Onstar indicating there was a problem with the battery(3 1/2+ years old)/starter. I showed up before 7 to get in line without an appointment. I showed the service tech to email I received. he gave me the cost of the test. He wasn't sure if they could get to it today as they were swamped. I was given a ride home by the courtesy driver. A few hours later I received a call that the test showed a bad battery cell and that they had a replacement battery in stock. I gave verbal authorization to replace the battery. An hour or so later, I received a call the car was ready. The service tech and courtesy driver were very personable.