Ziggo have changed some channel frequencies to a new 256-QAM modulation. It toke for a while to figure out the changes, but I did notice that some channels that where using the 256-QAM modulation did not work anymore.
After a week of testing and reading, I found out that my code did not look at the QAM modulation at all. It turns out, that Ziggo was doing only 64-QAM, so my list was always working. Now the Dreambox Ziggo Channel list software is looking at the modulation and take that in account with the frequency information.