To fix DSR sell items with free shipping, fastest postal service you can, make sure you have good descriptions and good pictures. If there is ever any issue, be ready to refund.
It will take some time but you need to start communicating, shipping fast, accurate pictures and descriptions etc.
Some ding you very low on purpose. Making sure the balance of buyers leave you all 5 stars by telling them I am leaving you feedback will you please do the same when you get time and leave 5 star ratings.