Customer Loyalty Discount Offered and then Told it Doesn't Exist???

Hi - I was hoping to get some feedback and see if anyone had any luck dealing with a situation similar to this with Xfinity.
I changed my internet service from 1000MB to 1300MB with Xfinity via an online offer that was available to my account in June. I went and picked up new equipment from a store and activated it at home. Everything appeared to go fine and I was able to use the new gateway with a new wifi network.
I checked my account at the start of July and saw that I was still being billed for my older, higher priced service and both the new and old equipment were still showing up in my account.
I tried to resolve it online but kept getting disconnected because the chat would time out while they were looking into things. I was told it times out with 1 minute of no activity, which is not very useful when they are spending multiple minutes looking into it.
I ended up calling customer support and spent two hours on the phone explaining the situation and trying to get the 1300MB service I had signed up for. They eventually came to the conclusion that the 1300MB service advertised was not available at my address and the service Xfinity offered and I signed up for could not be provided. They offered 1200MB service, apologized for the mix up and offered a customer loyalty discount.
They sent the offer via text message and I accepted it, then they were unable to process that. I was transferred over to a second agent and even though I was assured they would have notes of what transpired, I had to explain everything again. The agent also offered the customer loyalty discount but told me because they had changed my service from 1000MB to 1200MB that day, the customer loyalty discount could not be applied for 24 hours. The agent said she would call me the next day.
After not hearing from the agent, I called again and spent an hour on the phone with the most unhelpful agent I have ever dealt with. She told me that there was no way the system would have allowed the customer loyalty discount and the two prior agents could not have possibly offered this. I found this surprising since the system allowed them to send me a text message with the customer loyalty discount. I said she could listen to the Xfinity recording of the prior call and she responded that if Xfinity did that, the prior agents would be fired. As this point, I asked to speak to a supervisor, as I was now at 3 hours dealing with an Xfinity issue that was caused by Xfinity advertising a service that was not available and then taking hours to provide a lesser service. She continued to tell me there was no one available and it was now the end of the shift and instead of resolving the issue or providing any help, she hung up on me to go home.
So, curious; has anyone else has had to deal with something like this and if so, any luck getting Xfinity to provide the customer loyalty discount that they offered? I really do not want to go into hour four on their customer support line.