Yes that can be really frustrating when customer service seems to give up too soon. They don’t always know all the ins & outs either, which isn’t any help.
I’m sorry to hear you went for Kindle. Was the Clara HD not an option? (Clara would’ve worked with OverDrive, and having the library book synced to your Kobo account via the Clara would’ve meant it would sync to your Aura HD too... once/if WiFi worked of course.)
There has just been a new firmware release, version 4.12.12111, which has WiFi improvements. I still think your issue sounds more like a hardware problem (maybe try opening the device up and see if you see any obvious fault?), but updating to the new firmware wouldn’t hurt, just in case:
https://www.mobileread.com/forums/sh...d.php?t=313381