A few months ago, I was dealing with rescuing people's coins who had a wallet called Block.io, and they also had some kind of web wallet for bitcoin, litecoin, and dogecoin. It mainly worked for operators of General Bytes ATMs because they didn't have to run a node. It functioned as a 2-of-2 multisig with a non-standard scheme. So even though users had private keys, they couldn't import them and spend from any standard wallet. You need to create the signature in a different way.
They were quite strict - if some tainted coins came in, they blocked API access to the account for the entire ATM network and wouldn't respond to emails for 2-3 weeks. Just like that, they'd send an email saying, "Sorry, you violated the terms, goodbye." Pretty harsh. Of course, they acted like, "Well, you have the private keys, so take your coins. It has nothing to do with us; we're just a tool for creating signatures and making transactions." They had some redeem script on GitHub where you could supposedly save the coins, but it didn't work and used their retarded blockchain API, so it was all wrong.
I solved this for one person whose coins I saved, and I thought it would be a good business to help many people because there was real stress. They had money locked up that they couldn't move, and a company just abandoned them.
Now new people are writing to me, quite a lot of people, asking for help to save their dogecoins. It's always dogecoins, I don't know why. They write mainly from Latin American countries, Brazil, wherever, writing in Spanish or Portuguese. The reason is that the service has shutdown completely. No support email replies.
I think for retail clients, it worked so that the second key from the multisig was stored on their server and encrypted with a key that the clients had. So basically similar to ProtonMail, where the private key is stored on the server, but they don't have the passphrase, so they have to decrypt it locally somehow.
Block.io ended their operations, now they only do their paid Blockchain API, Sochain. So desperate people are writing to me that they don't have access to their coins, they didn't notice the email that Block.io was ending operations, and they don't have the second private key. I can't help them; it's a multisig, and they don't have the second key. It's a total mess because this is like a hardcore rug pull, but they didn't even steal the money; they just completely abandoned their customers. If they at least emailed the customers their encrypted secondary key, I could decrypt it and save the coins. But now they are behind an API that no longer exists.
Lots of people are writing to me whom I simply can't help because I can't sign the transaction. But it's quite bizarre that everyone has Dogecoin, really, 100% of them have Dogecoin and only Dogecoin.
Anyway, if you are stuck and you have both keys (not a secret pin), check out my recovery services. And always have your coins, in your wallet, not in some API or on an exchange. For many people, this was life-changing money. Gone.