I got dicked by B2C autoparts as well, sent the non-platinum plugs. Return was a major pain in the ass since I'm in Canada and had somebody bring the plugs back from the US for me. Reading on the internet, I found that the ECU will throw a misfire error in a hurry. The non-Pt plugs are for a smart car - don't use them.
This was also in summer that they sent the wrong plugs - obviously, they haven't learned from their mistake. I think the nickel plugs retail for about $3 a piece.