Weak service at webafrica

I cancelled my service with them as I couldn't afford it during the lockdown anymore. After cancelling I got an email saying that I should not worry about sending back the router at this point. All of a sudden a couple of weeks later I get a letter threatening me because I haven't returned the router. After that email I've been trying to get hold of someone at Webafrica to explain how I should return it.. no one answers a phone there. I've tried the Whatsapp chat link, but that was just as useless. No I just got a bill for R1999 for the router. I'm beyond fed up.