So starting from scratch is ... tricky.
I had my Amazon seller account banned for 15 years. I couldn't sign up for another one without it getting banned too. It was all because a scammer decided they wanted to give me negative feedback and keep the item I sold them (in addition to my refund).
No amount of talking or emailing ever got me to a person I could talk to. These companies should be fined/prosecuted for this. As a seller, there should be rules around getting banned and ways to appeal.