Fakir RS770 Robot Vacuum Won't Build Wi-Fi Connection

I'm like almost literally fighting my Fakir RS770 robot vacuum. It won't connect to Wi-Fi for a week after operating properly for a year. It stays at 75% and chills, tried numerous times, but they say it needs a 2.4 GHz connection. I got a Telekom 2.4 GHz internet connection for fun even though I've been using a 5 GHz Superbox for a year. Guess what? Same result. No matter what, I can't reach the support center, I hate this piece of junk!!! This used to clean my floors, but now it's a terrible letdown. I've tried everything, even switching to the 2.4 GHz network as they suggested, but nothing works.  helpless. The support center is unreachable despite my best efforts, what do you do other than this???  I'd love your advice if there is any. These guys won't help obviously.