I only know Salt and Coinloan that offer such loans. I never used one of them and do not know anybody ever used them so I can't really say much about it. Read you tried to contact Salt but didn't got a respond. Just try to contact Coinloan then. They are a highly competent team what I heard of.

Btw (just because I'm curious): Do you speak german? (since you wrote you have a German passport)