ZAG Motors Everett

I purchased my Chevy Silverado a few months ago and the engine light was on. We make a deal to purchase the truck and they were going to fix the light issue. After I take the truck to them three times the light it's still on the next day after i picked the truck it's time. When i asked what they did they won't even remembered what they fixed. The truth is they just reset the codes each time that's why the light comes on the next day. I called and informed then the problem it's still there but I had to go out of state for work, the guy told me to bring the truck when I return. When I called them to make appointment they told me that they already spent enough amount of time on the truck and I have to pay for a new diagnosis then they will fix the problem out of pocket, they supposed to know already what the problem is why they need new diagnosis...I told them I'll contact the person who sold the car to me which I did but I never got any respond neither. It's too bad because I just bought two more vehicles after that. They just lost one more customer. Just stay away from them...