Unjustified Charge for Faulty My Roborock S5 Max Charger

I made a bad choice when I bought a Roborock S5 Max from Teknosa. I was excited at first, but quickly became disappointed. After only a short time of use, the device stopped charging all of a sudden, leaving me with a useless robot vacuum. I took it back to Teknosa because I was upset and wanted a quick fix under the warranty. To my disappointment, though, they sent it to a company called Bood Technical Service. Even worse, Bood Technical Service said that the charging dock broke because the user did something wrong. This accusation is completely false because I haven't done anything to the charging dock since I got the product. And now they have the nerve to charge for a charger that doesn't work!