Hello guys,
I wanted to know how you usually deal with unreasonable clients.

In my field, I sell digital artwork.
My ToS state no refunds and there is also no mention that Intellectual property is automatically transfered. People are basically “adopting” artwork.
Based on my current situation and what’s best for my business, I made a decision that upset somebody. I offered a refund on a design (even though I woudn’t need to do that in the first place)
They now want me to refund every design they ever purchased, which I honestly don’t understand, since in this situation, only one specific design is of interest. (Everything is used personally, no commercial work is included here).

What I offered them is a contract, where I transfer rights officially on any designs from past purchases.

I personally find it quite impudent to ask a refund on other designs. (this is the very first time in 7 years, I made a certain decision based on what’s best for my business and myself, never have I had any trouble with anyone before)

I wanted to know, how would you handle the situation? How do you deal with customers that you feel are unreasonable in general?