Sold service on a lie by Xfinity, anyone got any ideas?

Hi, it looks like this hasn't been an experience unique just to me (unfortunately), but I was wondering if anyone here could give some advice? While I was preparing to move a new apartment and scouting for internet plans, I saw Xfinity was hosting a few deals for internet service based on my location. I noted that there was an even further discount for the internet service if I were to connect a phone line to the account. Now, I'm currently already part of an Xfinity family plan with three other people,  so I inquired if I could just somehow use that phone line to apply for the discount. I got a hold of an agent via the virtual online chat, "Rita", who told me that usually that discount is just for new lines, but she would see what she could do. She later came back and said YES, actually I COULD use my already existing line, I would just have to call mobile care once I made an account and had the internet service ordered and set up. I told her I would have to talk to my leasing-partner and I would get in touch with customer service again at a later date (as an added aside, Rita was VERY pushy about me setting up an account right there and then; its crossed my mind she may have just telling me what I wanted to hear so I would set up an account with her. She said that was the only way she would make commission, which only made the whole experience more unprofessional and uncomfortable to be honest, although I suppose that is not the point of this post).

A week later, shortly before my move-in date, I contacted Xfinity customer service again, through the virtual online chat feature. I was put in contact with someone who didn't give their name, but I explained the situation to them and told them what Rita had told me, just to clarify that what I had been told was accurate. Again, this agent confirmed that YES, this was something I could do, I just had to open a new account and get my internet set up, then get a hold of mobile care to get the phone situation sorted out. Relieved and confident in the information I was given, I allowed this agent to walk me through the account creation process, and I ordered my internet service to be delivered to my new apartment.

Now of course, the fun part: I set up the modem, got the wifi working, and got a hold of customer service. I spent five hours yesterday online chatting and calling multiple agents, all of whom said "oh actually, NO you can't do that, you're gonna need to set up a new phone line". I eventually got a hold of a supervisor who, after all of this, offered the solution of...gifting me a $100 prepaid card if I set up a new phone line. So. Here we are. I've got quite a bit of evidence to back me up, I made sure to back up all the chat logs with the online agents and save the transcripts, it just doesn't seem to matter to any of these people I'm talking to. Honestly this seems like an instance of fraud at this point, considering I was told false information in order to make a sale. Does anyone have any advice at all, legally or otherwise? It would genuinely mean the world to me at this point, I'm run down and ragged and have a new apartment to finish setting up, I don't want to give these people any more time than I already have.