I'm pretty new to Kobo (bought a Glo HD last month), but had already two problems with ebooks (the first had false content, the other I just wanted to give back). In both cases I contacted the costumer service via contact form, and in both cases the support was not only helpful but they refunded the amounts without any problems at all.
Maybe sometimes something goes awry and they can't satisfy a customer but that's not my experience and that's what this site is all about: subjective experiences. I love the idea of a website which only offers ebooks ereading content, and nothing else.
I think the kobo desktop software and the shop on the e-reader itself is too simpel regarding searching for specific kind of ebooks and so on. And the ebooks (at least in English, which I prefer although I'm German) are a little more expensive compared to Amazon. Most of the time anyway not always.
So, in my opinion, there are a few bugs (not to mention the strange differences between kepub and epub formattings which occasionally occur) and they are the reason for removing one star but I won't go back to Kindle and Amazon.