First oil change was a problem

I went to wallmart. I know that was the first mistake. Told them I need an oil change just the basic no problem. Then Rey asked the model and year. After I told him it was a 2011 gmc he told me that they can't do the basic oil change on any 2011 GM vehicles. But they could do the $60.00 oil change. Rather than $30.00 . I left and went to a dealer near by they said no problem $19.95 but I have to make an appointment. And that's what I did so I guess the moral is don't go to wallmart.