Can't cancel an order after 30 minutes have passed? Who do I complain to for terrible sales practices?

I was called by a salesman who basically forced me to buy an apple watch, and they told me I could get a deal since I'm a gold member if I just called mobile support after to apply a code. 

They didn't tell me I would have to place a new order to apply the code, or that I couldn't cancel my previous order.

Beyond frustrated with Xfinity's salesmen. I'm going to return the watch when I get it and I'll start looking into other carriers if this is the kind of shady work we're doing.