Unfortunately such situation do happens, and expect them to happen from time to time in many shapes and forms.
Personally, with more than 250 - 5 star reviews, much more gigs being sold, many if not all satisfied buyers, being a proud membership of Fiverr Pro, i still have rating of 4.9 due to few similar case.
On the other side, I have a slight different strategy (which probably do costs me 4.9 instead of 5). I ensure gigs are well defined to prevent cancelation. Clearly state what I do and what I don’t.
You would happen to have a buyers who would unintentionally or intentionally leave a bad rating. While I do offer cancelations when it comes to something thats:
a) Hitting a point that something can’t be done along the way, due to my inability to deliver industry standard quality.
b) Force Majeure, objective situation where something is not possible to complete without anyone to blame.
Sometimes it does happens that customer leave <5 stars rating by mistake, sometimes it’s a result of trying to ransom to get more than initially agreed or cancel already perfectly delivered project.
Whenever received such “threat” - i simply said ok - please go ahead. At the end of the day, it’s your discretional right to rate the way you want.
How I fight these ratings?
Simply by not spending much time on them, rather attracting more customers, trying to convert these who buy once to become regular buyers, and burry the bad rating by tons of positive ones.
As a result, you would probably not be 5 start rated, but 4.9 is absolutely acceptable for me.
I would suggest you to do the same. Once the project is completed respecting all the norms of a good industry practice dictates - leave the user to rate it the way he thinks without entering the discussion about that.
If you are constantly delivering extraordinary service - this will not hurt your rating. So rather than trying to find a solution for current rating, make sure you earn 5 stars on next orders. At the end of the day, once you have a huge sample, even one start rating can eventually bring you from 5 to 4.9 which customers will understand taking into account you have few hundred reviews - and it’s impossible to please everyone.
Rating system is very good one - it tells you precisely if you are on the right track once you build up a good sample (many gigs sold). I would suggest you focus on that rather than spending a valuable time trying to correct something that can’t be corrected.
At the end of the day, there’s much more legit buyers who are there to finish their business and will do a nice review both due to a fact they are satisfied with the work as well to have you onboard for further projects.
Take it easy and without frustration due to one bad rating.
I got 1 start from a customer who was “not only expecting me to build him a rocket, but to teach him how one is being built” - ordering a gig that has nothing to do with rockets. What can I do? Spend time thinking on him, or get 20 more customers, provide them with exceptional service and earn 20 more 5 stars. I always chose a second option
At the end of the day, we all have ability to rate each other without explaining why. Getting many negative reviews is actually helpful to show you something is not right with your gig / service / delivery or expectation out of your offers. Use this to improve.