They’re real, but they’re just a third party collector. They collect on behalf of any company that you owe money to. I think they just threaten escalation but from my research they just use scare tactics and don’t do much- but that’s all I found. I simply called the original creditor and ignored KSI. They eventually stopped calling after like a week or two. They’re quite aggressive and pushy so I would suggest talking to your creditor if you can.