After 90 days and messages left it’s his lose. I would sell it. I would document the event in writing. It anyone was there at the time of accepting the money i would have then sign a document and date it. It you would end up goig to court the judge would have the information. Also like someone stated. Storage at 75-100 bucks a month is going to add up. Do you have any friends that are lawyers? Give them a call or contact the small claims court in your city and see what they say.