Email address for corporate complaint

I contacted Xfinity employee via online chat to see if there was a package that would lower my bill and the representative swore that he found a package that included all the things my current.  The representative kept sending emails and text messages that I couldn't open so I couldn't review the plan, but he overrode the approval process anyways.  This morning I turned on my tv and one of my cable boxes was disabled so I messaged the Xfinity chat and they told me they couldn't fix the issue and to call the Xfinity customer service.  I contacted costumer service who informed me that the Xfinity who changed my plan disconnected my second box.  Then, in the process of this call, I asked to speak to a supervisor as the representative told me I would now have to start paying more money than my previous bills.  The employee said the supervisor was busy and would call me back.  Eight hours past, no call from the supervisor so I called Xfinity back as my tv still wasn't working.  During the call I also realized that my internet speeds were reduced and this employee kept trying to sell me on other Xfinity services instead of fixing my issue and when I finally had enough, I told the employee, "I don't care about you up selling, I want my internet speeds put back to what they were, I want my cable box reactivated, and I want my bill plan to reverted back as I didn't authorize this being changed like this."  The employee told me to get my speeds back and my cable box working I'd be paying more and there's nothing else he could do.  I requested to speak with a supervisor and for the next 20 minutes, the employee again kept trying to up sell me and I had to repeatedly tell him to stop.  Once the supervisor got online, the supervisor told me that he could see that the original representative overrode the customer approval requirement so he could verify I didn't know what was happening and then stated he couldn't do anything to help me.  George, the supervisor, told me to go to an Xfinity store and that they could revert my plan back to what it was.  I asked George if this was true and he stated this was a standard practice as the employees in the Xfinity stores have more approval authority and access than him.  I setup and drove to the Xfinity store to only be told the call center representatives and supervisors commonly mislead customers to changing their plans, causing customers to be billed higher than expected or don't receive the services promised, and mislead customers into believing that Xfinity stores can fix their issues to get people off the phone.  I asked the store supervisor, "if a Xfinity employee causes issues for the customer then the customer is hosed because the employee screwed up?"  The supervisor said, "Unfortunately, that's true."

Now, I had to change my plan yet again to get my internet speed back and get my second box box working which is causing me to get bill higher than what I was previously paying.  I am totally disgusted by Xfinity's business practices and their company lack of respect for their customers.  How do I get an email address to send a complain to corporate?