They successfully charged my card for $1 like a dozen times as I tried and failed to get past their check. At the time I wasn't even interested in the free stuff, I wanted to pay for an ARM VPS, and their verification system just wasn't satisfied with something. After getting frustrated I tried to sign up for Hetzner instead and they allowed me to register and spin up a VPS without even having any payment information on file, they just trusted that I would pay the invoice at the end of the month. Funny how different the two companies treat this stuff.
I contacted them by email and was eventually able to create an account. Had to contact them again at another point where their system once again checks for something with a credit card and again rejected me. I can't remember exactly for what.
It worked eventually and I use the free tier server for small things, but of course it means I can't ever consider using their service for anything serious.
Yes, I sent them an email, I tried 3 debit cards and a credit card over a span of 1 year. They told me they cannot resolve the issue or process the transaction. They refused to provide any extra information.