Fwiw, I'm pretty sure that the CSR was correct. While it's a single identifiable piece, it's not a single part to Weber. It only comes as part of the kit. Sima thing would probably happen if you tried to get a single fin replaced as it doesn't look Iike it has an individual part number either.
My frustration wasn't that the single piece doesn't have a part number. My frustration was that she wouldn't listen to me that I was not calling about a grill that was missing a piece, that it was a piece from a replacement part. I kept telling her this and she kept asking me what grill I had. My point is that it should not have taken such a long time for her to know that some individual parts are not available or at least be able to look up part #7444 immediately and be able to tell that that the "H" washer is not available separately. I was actually trying to save Weber (and Amazon) some money by saving them both the trouble and expense, albeit minor, of return shipping costs and ultimately the return from Amazon to Weber.