Verizon still billing for returned equipment - Unresolved

[Vwik]

I had an issue with the Verizon router and was advised to return the equipment. This was within the first 30 days of the contract, so I was told I would get a full refund for the router charge. I went to the store and returned it (Have the receipt), and they ended up cancelling my account (First indication of terrible service). I had to stay on the phone all day while fixing the issue (I had to basically create a whole new account).  On the old account, I paid off the bill, and was told the router equipment charge would be credited to the account. I have called multiple time to try to get this cleared (as I dont want this to impact my credit). Everytime the agent initially says you owe the amount for the equipment, which then I have to reexplain the whole story - to them saying they will make a note and this amount will be credited.  I am still receiving calls to this day for this bill - this return occured in Dec 2018. I was contacted from a debt agency as well despite being told multiple times it is resolved.
I need to speak with a human to resolve this - I will be cancelling my services if I dont stop getting harrased. 

[kh-gary]

Hi Vwik,

Your issue has been escalated to a Verizon agent. Please check your Private Message Inbox for a message from Verizon_Support. You can find your Inbox by clicking on your username at the top right corner of this page. Please direct all correspondence concerning your issue to the agents, who will be assisting you privately.