I need to understand how to file a formal complaint with corporate. Been trying to reach a supervisor for 3 weeks now.

I have been with Comcast for over 13 years now and never have I experienced anything like this with any other US company. Usually, every 2-3 years, someone from comcast emails/calls me and we discuss the terms of the new contract. Then they send me a DocuSign, and I renew the contract. This time no one contacted me, and when my contract had expired, I was charged triple for the services. I have noticed it on the 2nd billing and contacted comcast, thinking this must be a mistake they will correct. Little did I know that this would become almost a month-long process where the so-called "Loyalty department" had explained to me on various occasions a number of these things:

- It is my responsibility to check when my contract is up (in my statements, not a specific email about it), and even though that's not how it worked for 13 years, it is not their problem, and I have to take responsibility for my actions (someone actually told me that).

- After requesting a supervisor to talk to me about this to see if he/she can work with me on this, since I was charged without my knowledge an extra 500% of my bill, I was told it would be 3 days, but also that the supervisor won't help me. 

- After waiting for 3 days with no call, I called back and was told that no one requested a supervisor call, but they are gonna do it right now

- After waiting for another 3 days with no call, I called back and was told they are sorry and they will call me back. This went on for 3 weeks.

- On the last call, another so-called "Loyalty department" agent - [Edit: Personal Information] - after telling me that NO supervisor was requested for me (once again), told me that he can either offer me a $200 credit OR a supervisor can call me back. He said that IF the supervisor calls me back, the credit would be void. It's one or the other, ha and I have to choose right now.

- During all of this time, I haven't signed a new contract since I wasn't able to communicate with anyone about my issue or get anyone to call me back. Meanwhile, the bill is accruing at that "crazy" rate. Roman told me that he can get me some "promotion" if I sign the contract again. After 3 weeks of going back and forth, I gave up and was ready to sign, only to find out from him that "he never mentioned any promotions". 

At this point, I have been trying to reach a supervisor for almost 3 weeks and have made a dozen calls to Comcast. The most surprising thing was the way I was treated in the "Loyalty" department. It's almost like what their goal in that department is to decrease loyalty to Comcast and lose its long-term customers. All I wanted was for someone to understand that I had Comcast for 13 years, and I understand that the way they do things might change, but there needs to be some leniency with their long-term customers. 

I have already transferred the phone line over to T-Mobile and am researching options for the internet.