SamyGO

Samsung claim that, they have some issue on their download servers, and they said those files will be in place soon, but It looks like not restored until now...
I wish they will put those files soon. But if they don't, you can find that file on internet too. I just search it with "T-CHLCIPDEUC" word on some search engine and found exact version. I prefer original firmwares from samsung but if samsung doesn't allow us to download them, than people will find alternative ways.

What is your current firmware version?
I think you know that it's risky to downgrade CI+ versions...

I think this post could be usefull for you.

If you do not get success and your wish to roll back firmware is very strong despite any danger, you could test special FFB version on your CI+ device (it could brick your TV, but if we prepare required dumps, we could restore TV back).