Unauthorized debit order from Vox

I have canceled my Vox fiber line and paid the cancellation penalty fee as supposed to, the router has been collected and delivered to Phindile at Vox Telecoms on the 14th of November 2019, yet they deducted R1091 from my account yesterday the 2nd of December 2019 and say that I did not return the router?! I have phoned them about it and they have informed me to log a ticket with *** but there is no response on it. Stay away from Vox as I have seen many people complain about Unauthorized debit orders!