[Google] Amazon listing has suddenly taken #1 spot for our brand name

We've always held the #1 spot on Google for our brand name. Unfortunately, as of today the Amazon listing of our product is now listed above our official website when searching the brand name. I would really like to know how/why that happened if the Amazon listing AND the official site have not had their content changed recently.

1) I don't remember why, but I've always been under the assumption that Google favors the official brand sites over Amazon listings. Is this completely untrue?

2) Could a larger volume of traffic on the Amazon listing be enough to bump it to the top, even if the content of the listing has not changed recently? I don't know how relevant this is, but Amazon recently started running search text ads on this listing before they made it to the top. I started a brand-specific search campaign to outbid their ads and was able to do so. However.. if the volume of traffic makes a difference then I would assume those ads helped make this happen.