Beyond frustrated

I have bought Yuka mini 2, new sealed unit, from a guy on marketplace, unboxed, binded to my account and used for a month successfully, suddenly it was disabled and I can’t use it now. I emailed support and all I was told is go ask previous owner to unbind it from their account.

But surely that’s not the case if it was binded to mine and I was already using it for a month? It was brand new sealed unit so I have no concerns that they might used it in the past, and they would not be able to add to their account because I’m using it already?

Any tips to where to go and what to do next would be appreciated