Koler one-piece seat replacement
I have a similar problem, the seat anchors are broken and kohler does not provide replacement anchors with the seat that they recommend for the model toilet.
I contacted kohler through the website e-mail address and they wanted $47 for the 2 anchors and a special tool to remove the old anchors. I replied that I did not need the $46 tool, just the $1 anchors. Their response was to offer a small discount.
Desperate to attach the seat, I inserted a large plastic anchor and, although loose, the seat is attached.
I have since found a manufacturer, Bemis, who apparently sells a kit to attach their seat to the Kohler one-piece. I've not contacted them yet, but I'll post if I'm successful.
What really bother's me about Kohler, is that at the same time I bought the toilets, I replaced the faucets with Moen products, which come with a lifetime guarantee. After a few years, the white coating on the faucets chipped and Moen replaced both faucets at no charge. I suppose Kohler is comfortable enough with their position in the market to not care about repeat business.
Good luck.