I had a customer order 4 YCHs off of me on the same base and used discord to discuss it with me and the options.
They sent me through the forms and I did a little clarification and then went ahead and sent WIPS of the product before colouring, got the all clear and completed them. I then sent through one which didn't look right and asked if they found a flat version of the pattern on google as this one was textured. I agreed to fix anything they would want as their form was very descriptive. They then proceeded to say this art wasn't as good as the other I have done even though its to the same par. They then decided to just cancel the whole commission even though it was completed and just wanted colour changes. I informed them that I don't do refunds to people who already have their YCHs done, especially when I have sent them the files, to which they explained the YCH doesn't even have shading which I never offered on that base as not all my bases have shading included.
Then after all this they decided to threaten me if I didn't refund them and called it trash and junk.