Xfinity Billing help continued. `

Okay so a few weeks ago I posted on here about my bill being about over $900 due to an agent messing up my transfer when I moved. 
I since then have had that partially fixed by an xfinity home agent providing a $300 something credit to my account. During this same day I had also spoken to another agent about my bill and what I can do after the credit showed on my balance since I had already told countless of agents on chat, and phone that I wouldn't do any payments on my account til my balance was fixed. 

So, I was told that after the credit was showing on my account I could then afterwards talk to customer support and request for the remaining balance, which now sits at $600, to be paid in installment plans, which in turn would avoid any suspensions or disconnections on my account. 

But of course, my services were almost immediately suspended when that credit showed up. I forgot to cancel a scheduled payment, and every time I try to do any kind of "flexible payment options" from xfinity chat, it gives me "I'm sorry, we're experiencing issues" and then I have to completely close and reopen my browser to try and chat again. As well as every time I now try to chat with an agent, all it will tell me is "were experiencing longer wait times, please try again later". Which is plainly [Edited: "Profanity"]. 

So, if basically all of xfinity's customer support options, and payment options, including installment plans which I ONLY FOUND OUT ABOUT FROM THE XFINITY.COM WEBSITE, are complete lies, why [Edited: "Profanity"] should I pay $600, or even a single [Edited: "Language"] penny for a company that doesn't uphold their own policies.

Am I able to get actual real help yet? Or should I contact the BBB about this as well.