Supersonic not so super

We cancelled our WiFi with Supersonic a month in advance in October 2020 as requested by Supersonic. It became a back and forth via email trying to get someone to play their part in their offices. I eventually reached someone competent and professional enough who held everyone accountable by giving me a reference number and actioning it via the system as he could see that my cancellation request was sent a month before. I am now struggling to get my refund from this company as they went in to our bank account and deducted an amount for November but the account was supposed to end at the end of October. I am now receiving calls from their courier company they partner with trying to collect the router which I refuse to hand over until I receive my refund. I was sent an email by one of Supersonic's employees saying that they can invoice me for the router should I wish to keep it. I then answered the email by making it absolutely clear that I do not want their router and that are in no way authorised to debit my account. I also informed the consultant/agent that I am happy to return the router as soon as I receive my refund. I have since then received another email informing me that the refund has been action but I take this with a pinch of salt as that would be the second email stating the same with no refund in sight. So disappointed.