billing issues

First i have been a customer of Comcast for very long time and never missed paying a bill.

I had closed our account recently with Comcast and was due a refund of $293.37 (Ticket # , confirmed by Comcast. The company could never get the refund completed; I have spent literally 5 hours trying to get this done through their chat service... and I believe spoke to someone as well. Comcast texts me the refund will be processed and never happens ..this is all on chat message...

                 We were able to complete your ticket [Edited: "Personal Information"] regarding your Account refund request

Recently I decided to take matters into my own hands and requested credit company to reverse last 2 payments, since there's no way to reverse only partial charges. Then I can pay Comcast the difference ( 359.20 two payments less 293.37refund = 65.83 due)

Comcast sends me a new bill for$359.40 and to collection agency??? 

Again today, as I write this, I have spent another 1.5 hours trying to get this resolved...chat assistant and live agent is nonresponsive when I request to speak to someone...just keep passing this along to next agent and never gets resolved!!

Can anyone please assist directly?

[Edited: "Personal Information"]