Wow, seriously? You really think someone believes this bullshit? "Design themes". Ah sure, copying icons and backgrounds from google images is definitely designing and takes tallent and effort, lol. What you basically did is look for some fitting images and symbols and replace it with the default icons and wallpaper in the portal.
I could instantly find some of your icons in the internet, e.g. these ones: music icon, tv icon, video formats icon and I am sure that basically all icons are just copied, the backgrounds look extremely simple too, basically just a blue image, some circuit background, the well-known circle thing and just some color gradient/fade background which I've seen atleast a dozen times.
Don't get me wrong, it's fully okay taking money for it. There surely is some effort in it, putting everything together. But this NEVER justifies a price of more than 5 € in my opinion. And it's okay that your opinion varies, but then you have to deal with critism and such. But in my view this is rather a scam than some kind of customer service. And I'm sure there are only very very few people which really would buy a new background and simple icons for 25 $. If you'd set the price very low, you could also target the average consumer which would perhaps be interested in a new theme for 5 bucks. But these prices are a no go, especially because you claim it takes effort and talent to "design" a theme which you've basically just put together by stealing others images.
You can have your opinion about it, but I'm sure most people will agree with me on that point.