Even if you did not have the negatives, the fact that you have not had any feedback for over a year is why you are restricted. You have to start as if you have never sold on ebay. Ebay treats zero feedback in the past 12 months as if you never sold anything. Until you build up your selling feedback and have no disputes, your limits will be lifted.
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Non payers should get unpaid item strikes and be added to block bidders lists. Period.