Forced to pay more/lied to?

Morning, 

TLDR at the bottom.
I have never posted something like this before but I am honestly not sure what else to do. I became a new customer last Friday and set up my plan for the 1000 speed with two fine lines all for $80/month before tax. (Using own equipment and had a promo for a free phone line for a year I believe). I chatted in that night to get help with activating my phone lines and the rep had mentioned he could upgrade my plan to the 1200 and give me 150+ channels with my two lines and reduce my bill by $10.00/month. I asked several questions as it seemed to good to be true but he assured me everything would be fine. I said yes, he sent me a form, and he said the changes and the lines were all set and should be fine in the morning. Next day I see the phone lines are still not connected so I chat in again trying to figure that out and connect the internet. I started at 845am chatting and between that and the calls I didn't finish (And I wish this was an exaggeration) until around 9pm. Whole Saturday gone! Now in that 12 hour span we were able to change over the phone lines and set up the internet which is good HOWEVER, come to find out my speed was actually dropped to the 300 plan. I told the several reps I was chatting with/called that this was a mistake and I was told it would be increased to the 1200 speed. I told them to look at the chat I had the previous night as its all said there if they needed proof. Many of them said they were not a supervisor so they couldnt access the records or send them to me and offered to increase my internet speed but I would have to pay over $100.00! I eventually got so upset I told them I didnt even want that deal that rep told me about anymore and just want to go back to the original plan I had purchased just the day prior but they said it was only for new customers. I explained I was a new customer but they said as I already started/changed I dont qualify for that promo. I explained to them I was lied to by another rep and that wasn't fair but it didn't seem like there was anything they could do about it. Eventually I was able to get a supervisor on the line who said they were able to see the notes and did confirm I was told I could have that super promo but thats obviously not what happened. She then told me she would bring me to my original plan and bring down my rate to around $70/month. She sent my forms and on these forms it had my rate at $108/month. I expressed this and she said not to worry that the promo would phone would come off of it and bring the price lower. I reviewed my upcoming bill today and, you probably guessed it, the bill is at $108.00. TLDR: Signed up for a new customer discount, Rep offered me a better deal with higher speed, speed actually was massively lowered and so I was lied to, wasnt allowed to go back to what I was at, supervisor said she would adjust it and it would be lower then I originally had, turns out I am now at +$28 per month for the same service I requested because a rep lied to me...also I spent my entire Friday night and Saturday trying to resolve this. Has this happened to anyone else? Can I get some resolution on this? Can someone at Xfinity help me? Do I need to involve legal counsel?