Where to complaint the Live Agent marketing problem?

I just did chatting with a live agent for my TV Box issue and At the very end of our chat, it seems everything went well and I was asked to check my email for confirmation while he was waiting. Then I lost the chat. so I tried to get a new one and retell my issue. it appeared that that agent was helping me then out of nowhere that person started selling me their phones or phone line for free. I was so annoyed . I said I don't need it. stopped selling it. just solved my issues. That person said " I was not trying to sell you anything but wanted to offer the promotion so that you were aware". Then the person just disappeared . IS it helping or what? Then the chat screen said the chat was inactive for 24 hours? It was not true. that's the lie. I am really mad. That marketing person just vanished not even solving about my problem. and another new one came in. I don't feel like I was treated with any respect. I am a customer for Xfinity since it was Comcast. This is very rude. In USA, I don't think your customers are not that desperate to get a free phone if they can afford your not very cheap TV and internet services. Time to think your strategy and retrain your agent.