Dean Patterson Mazda

I have a 2010 Chevy Equinox. I received an email from OnStar that they detected something and a diagnostic check needed done so I did that. I received info back that my car needed looked at so I made an appointment with Dean Patterson that day since I bought my car there. I told the man on the phone what OnStar had said to me thinking he would make a note or too. Well I show up to my appointment and the guy at the desk asks if there is any engine light on. I said no but OnStar detected something and said to get it checked. He said without an engine light on there isn't really anything he could check.  The question going through my head was why didn't the person who I spoke with to make the appointment tell me that?? I specifically told that man that no lights came on, just an email from OnStar. I will never bring my car back here for even an oil change. I will never buy a car here ever again. Go to Cover in Windber. Have heard wonderful things about them.