[GeoffR]

If you want a refund on the book, you can contact Kobo, but Kobo can't do anything to fix the publisher's mistakes.

If you want the mistakes fixed you could contact the publisher. But in most cases it is a waste of time. The exceptions are Gateway SF and some small publishers, who will actually reply and fix the errors within a few months. But in my experience most big publishers will do nothing.

I have found the best option for me is just to fix the mistakes myself. That way I know it will be done properly, and it is usually faster and easier to fix the mistakes than it is to go through the process of contacting the publisher and explaining what and where the mistakes are.

Edit: I can't remember when it started, but it seems Kobo is now pushing the corrected ebooks direct to my library. I noticed that some books that I had reported errors for direct to Gateway SF were later re-downloaded during sync even though I hadn't contacted Kobo about them. It used to be that I had to contact Kobo and ask for a corrected version.

Edit2: Fixing the mistakes myself is perhaps also a form of catharsis. Without it the number of mistakes in ebooks would have driven me insane, or at least back to reading paper books.