Stolen iPhone

How did you have it "blacklisted? Check with that party.

I don't believe there is a single "blacklist" maintained by any one party.

1. Probably what you are referring to is you have reported that you lost device to your wireless carrier, so they can disable your account to prevent calls, texts, and data use. Your device might be covered under your wireless carrier plan.
2. Apple Inc cannot confirm this

However you need to take few steps to protect your data. Click the link below

If your iPhone, iPad, or iPod touch is lost or stolen - Apple Support

https://support.apple.com/en-in/HT201472