People please. A LOT of possibly false assumptions here.
OP, you stated:
"He said just to walk back to the area with my wheels when I came in and everything was good to go."
That doesn't sound (to me) like an appointment. You obviously thought it was. The person (there is no service rep, just various sales folks) may have thought you'd be coming in first thing in the morning. So if you'd gotten there at opening time, getting it done by end of day would be no problem. May have been a miscommunication by both of you.
You also wrote:
"Then comes today. I spend my morning getting the wheels off of my bike. I drive 23 miles to cycle gear."
When you came in, were you feeling a little rushed or frustrated because it was harder/took you longer than you were expecting?
What time did you get there? If it was the middle of the day, the guy you spoke to might have been on break/lunch whatever. Just shootin the shit with his fellow employee.
Also, depending on the time, it might have been a little late for two more tire changes.
OP, please try to understand, I don't work for CG, nor have I ever. But I have worked in retail a long time and have witnessed situations like yours happen and turn into landslides in a hurry. I am just trying to get you to understand that the employee may have been joking or trying to be clever. And may indeed have meant no harm. Just messing around with you. The manager was probably standing by her fellow employee, as she should, given the situation as she saw it.
You then wrote:
"At this point I was infuriated by his attitude, treating me like I was an idiot who can be spoken to as if I had it coming. All the while as he leans against this shelf, when he said how many tires he has waiting to get done I tell him that "maybe he should get to work then", completely fed up."
You seem to have been a bit predisposed to being upset when you got there from the way you worded your original post. I may be wrong, but your reaction to what the first guy said seems a little extreme. Were you possibly being a little oversensitive?
Just some questions to ask yourself before rallying the Lynch mob...good luck with whatever happens. Moto Shop in SF is open til 7:00 pm. You'll have to do them yourself (with their supervision) but a great skill to have.