How about preventing those buyers who asked to cancel or done something wrong which led to cancellation  from leaving any feedback as a start?

A buyer asked me to cancel their purchase. It happened because they failed to read even a short item title.

Their reason was that they misunderstood postage cost while it seemed they did not read the item title not to mention its description at all. This item was for my customers who received quotes from me and I specifically ask in the item title  not to buy the item without getting a quote from me first. 

I cancelled and suggested politely that it is always better to read a title and description before purchasing. Just to make sure they understand what they are buying. 

And yet this buyer was allowed to leave me a  neutral feedback blaming us for their mistakes.