Xfinity Assistant Agent gave false info to sell new plan and tried to avoid answer – I want to file a claim

Xfinity Assistant agents avoided my questions, gave false information, and tried to push a new plan on me.

I contacted them through Xfinity Assistant to ask about extending my current internet promotion. My promotion clearly ends in September, but the agent told me it would end next month. Then they tried to get me to sign up for a new plan.

They kept asking if I wanted to proceed, and I said no. I told them I would wait and watch. After that, they lied and said I would be charged double next month. But in reality, after a month, my promotion was still active, and I was charged the regular amount, just as expected.

So I tried to file a claim through Xfinity Assistant, but the agents there gave me strange explanations I did not ask for. I only asked how to file a claim, but they kept forcing explanations I did not want. They gave me an email address as Comcast.net, without a proper contact.

I have the full chat history with both agents.
I am now officially raising this issue with Xfinity and demand to know how I can submit a formal complaint through the correct channel. I do not want to use Xfinity Assistant.

Please respond with the proper process.