Rock Auto Rockauto.com not dealing fair Internet, New Jersey

After placing an order for Centric brake pads and rotors on
a Friday night, I compared Rock Autos shipping cost of $75 to the tire racks
shipping charge of $31 for the same parts, and called to cancel the order two
hours after placing the order.  I was told the brake parts for my Mazda protg were special order and Centric,  Rock autos supplier, normally would not cancel an order. 

I dont understand how pads and rotors for a Mazda protg
would be special order and how when I placed an order on a Friday night, that
two hours later, I could not cancel the order. 
The person I spoke with offered no other option except saying they would
email me on Monday if the order could be canceled, but said it was doubtful.

On Monday, I got a UPS tracking number but the parts had not
shipped, yet I was not allowed to cancel the order.  The parts shipped on Tuesday.

I see they have a lot of positive reviews, but is it just
me, or do most of the review look like they were written by sales people and
not actual customers? 

My advice is to stay away from Rock Auto and use a more
reputable part supplier.