Transfer of service resulted in double billing and losing our Xfinity mobile discount

I initiated a transfer of service request to move service from our old apartment to our new house. The rep on the line offered me a new promotion at the new address which I accepted. We moved the service over, vacated the apartment and moved into our new house. I had set my bills to autopay so did not notice this, but just today found out that the service was not properly shut down at the old address and we were being double billed for our service. Additionally, our mobile discounts (which we were receiving for a year and still have a year of validity) stopped showing on our new bill. When I contacted customer service today, I was transferred back and forth from the Internet department to the Mobile department back to the internet department and finally to the escalation department. I was told that our bill will be backdated to the beginning of October since they detect usage on the account until then. We moved out of the apartment and surrendered our keys in the last week of August, so there is no way the connection could have been used until October. With regards to the mobile discount, the rep first said that I was getting a mobile discount and my final bill was after the discount and that it would not show on the bill. However, after I pulled up the bill and read the line items to him, he conceded that there was no mobile discount and that it could not be added back unless I get another new line with Xfinity Mobile. At this point, I asked to speak to a manager and I was told that I was already with the escalations and retentions department and there was nothing else they could do. I was asked to wait for the final statement on the old address which was only backdated to October, thereby double billing me for two months while taking away our mobile discounts (which was the very reason I moved to Xfinity Mobile in the first place). Has anyone had success getting help from customer support or at the store for such issues? I have been a Comcast customer for almost a decade and this whole experience makes me want to completely switch out of both the Mobile and Internet services.