I have an order which I gotta deliver today (delivery time was 10 days), and buyer contacted me today saying he wanna change the design to sth else, but I already finished the conversion for the design which he provided me while placing the order. I said I can do it, but I will charge accordingly, but he said he can’t pay extra. After a long talk of “please do it” and “I am sorry, I can’t”, he seems to accept(unwillingly) the truth that I really can’t, however I know the design which he provided me before is not useful for him anymore.
I am afraid he may leave a negative review due to this… probably, not sure. What should I do in this case?