My main issue is that there is no recourse. I did everything right, I had a /19 with all the correct WHOIS information, my server had nothing illegal on it or things that spamhaus doesn't like. (those two things aren't necessarily the same, that's the other thing that really annoys me)
And to pressure my ISP they decided to make it impossible for ME to use the server I paid for. I understand what they are trying to do, but the way they are doing it leaves a lot to be desired. If they actually cared about the damage they did they would have unblocked my /19 for at least a reasonable period of time for me to migrate. It's not like I got a warning or anything, I only found out I was shitlisted after people started to complain.
After that it took me several days to get everything moved over, DNS changed etc, and again: no recourse, no way of temporarily getting my service restored. The only thing I got was a warm fuck you from Spamhaus.