Broken item rejected

I’ve been a loyal customer for years. I bought my son a gaming keyboard, mouse and headset pack and then the headset stopped working during level 5 lockdown While he was using it for online classes. . We tried to fix it because he needed it for class everyday, it was fully functional and then lockdown was eased and I sent it back but got a message to say it’s been declined because we tried to fix it ourselves. What were we supposed to do? We needed it for his classes and we never expected that the time would break so easily! Clearly the quality was bad! And we paid quite a penny for it!