Bad billing procedure for router return and horrible customer service

They billed me R2000 for a router I'm supposed to return. The only notification before being billed R2000 is an email. That amount of money warrants a bit more than just an email? Also, it was on my secondary email because I couldn't use my primary email as their system doesn't allow you to use your primary email after you've canceled your account.

Lastly their support is useless at the moment. I was on the phone for 37 minutes no answer and requested a call back, 2 days later still no call back. Their whatsapp is useless, I started a conversation at 10AM and only got a replay at 4pm and was in a meeting causing the chat to be canceled in 10 minutes... I've tried website tickets, call center and whatsapp and have run out of options. I can't just be billed R2000 out of nowhere.

I would like a refund for the R2000 and will gladly return the router as I haven't used it since May when I originally cancelled.