Incorrect Internet Pricing and Refusal to return credits

I am very disappointed with the way Xfinity sells the service. Being with them for a year with internet and mobile bundle just makes me realize that I put my trust in the wrong place. I usually just have to pay $36.43 for the Internet for 12 months. Before the term went to an end, I knew that promotional discounts would expire as well. That said, I reached out to them with the hope of finding some deal not too much for my income (I am a student). I talked to some agents who offered me the same deal - Connect More @ 300 mbps but at different prices - one said $55 and the other $65. When I corrected the agent that offered the higher price, they reduced the price to $55 with nothing changed in the deal. It would not be worth being posted up here for anyone using Xfinity services to alert unless they had charged me $84 for the first month of the second service year. When I contacted Xfinity agents, they just put in the simplest way as they can that "your promotional discounts ended" - which is why I proactively reached out to them before it happened. The agent then suggested me to open another phone line to diminish the internet cost to $55 for slower speed 100 mbps which is what I had been told before the old term was over. They promised to give me $30 credit for that but the email confimation never came.