Tmobile can only remove the blacklist from the person who reported it lost or stolen.

Contact ebay support to try to get a refund.

I reported my iphone lost but a business later discovered and returned it. I purchased the device from T-Mobile and the associated service plan is still active. I'd like to have it removed from the blacklist. I prefer chat over voice.

Did you get an insurance replacement? If so you need to return it.

Otherwise you need to call support to lift the block.

I also Am having same problem I have purchased a black listed phone from e bay 359147522510938 and Am unable to access my phone device which holds all my business accounts and I am a business owner and do all my business on my phone 

If the phone is blacklisted how did you get your information on it?