How to file a complaint/appeal for a credit

I have written a letter requesting a credit for what I believe to be a billing error.  I have been all over the verizon site and cannot find where to send it.  I wasn't able to resolve the issue over the phone and the supervisor advised me that I could write a letter to the address on my bill, but there isn't one.

Re: How to file a complaint/appeal for a credit
Moderator Emeritus
Hi zildjiansara,

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.