Business unresponsive

I purchased a new UPS from Super Electronics, received it, plugged it in,charged it for 6 hours,. Plugged my WiFi router,it worked for 5 minutes, beeped and went completely off. I contacted this company via email, WhatsApp,phoned. Nobody is responding,asked me yesterday, what's the order number, that's it. How do these people do business? I don't know what's the problem? I am very disappointed ☹️ Thank you for nothing.