Topic: C-stick going crazy/affecting touchscreen

Long story short, I had to send my console to Nintendo to repair the upper screen, and it came back with an issue that when I bend the screen at a certain angle to close it, it affects the upper right corner of the touchscreen. I originally overlooked it as it didn't seem to affect games.

Then I noticed the same occurs when I use the C-Stick and the problem worsens. For example, in certain games that allow you to scroll menus with the touchscreen, it scrolls upwards infinitely and in games with buttons on the top right corner (Like in Dead or Alive there is a button that asks you to spend 10 coins to buy a gift) it just keeps on pressing them as well.

Should I bother looking up solutions or just demand a replacement?

Try calibrating your touch screen.