Frustrating customer service experience - 8 employees failed to fix my account

I have the most difficult time with Xfinity's customer service representatives to solve a billing issue from September. I have been lied to several times. I have been assured that the billing error was fixed. It wasn't. I asked for the updated invoice to be emailed to me, it wasn't. I was told I would have a credit applied to my next bill, it wasn't. 

When I requested a refund of the overcharge, I was told by Ray (employee ID I#T - not sure if that's real) that the only way I could get a refund was to contact my credit card company and dispute the charges. When I asked to speak to Ray's supervisor, he said he didn't have one.

When I attempted to obtain a means to file a formal complaint, I was told I could speak to someone. When I stated I wanted to have my complaint submitted in writing I was given the run around for 3 hours. I was able to get a PO Box address and the email address - abuse@comcast.net. When I asked for Mohammed's employee ID number, he said he couldn't provide that information since it was personal information.  I tried to explain that it wasn't personal information. Mohammad insisted that according to Comcast's policy he was not to give out his employee ID. 

After going in circles with Mohammed and his employee id, I asked for his supervisor's name. AGAIN, Mohammed say he could not provide that information since it was personal information.  I went in circles again stating that his supervisors name was not personal information.

I then asked for the chat ID number that was offered to me previously, when I asked for his employee number.  I was provided the chat log number of xxxxxx.

Needless to say, my whole experience with Xfinity's customer service has been exceedingly frustrating and unprofessional.  Xfinity should be ashamed of how their employees have acted. No accountability, no responsibility, and just have been pushing customers’ problems further down the road.

The worst part was when I found the appropriate place to submit my formal complaint - the complaint forum. I wrote out the entity of my complaint and when I submitted it, there was an error message and my complaint was completely erased.

Nothing Xfinity does seems to work correctly. All I want from Xfinity is for their employees to do their jobs.