Ask HN: Pre-ordered an ebook. No updates for 2 years and author is ignoring me

I pre-ordered an ebook on a (rather niche) software development topic about 3 years ago and it was not cheap. I was eager to receive the first version of the book but never did. The last update mail I received from the author is 2 years old now and he claimed that "the book is going nicely" and he would "send some updates soon". Over the past 3 months I have tried to reach the author multiple times by e-mail and through Twitter. Yesterday I also tried LinkedIn but it seems like the author is ignoring me. Through his social profiles I can clearly see he is very much alive.

What would you do in my situation? Obviously the lack of communication and ignoring my messages is what is bothering me the most.