Xfinity customer service in store and help with internet service

We decided to downgrade our tv/internet package and move to internet only recently. Figuring it was best, we went into the local store to get this taken care of. We have two modem/gateway boxes on our property and have had so for nearly 9 years. We have one box for the main house and the other for the apartments in a detached garage. Booster and other methods do not work given the distance between the two buildings. Xfinity ran two lines, one from the pole to the main house and the one from the main house to the detached garage. We have always paid to have both of them. When we changed to an internet only service we were told they no longer do the two boxes on one property any more, but we would be grandfathered in. And so we thought nothing would change. We thought this was great, and there were no red flags or a concern over asking more questions as the customer service rep said there would be no issues. Fast-forward, we get home and realized that we no longer had service to the apartments in the detached garage. We went back in the store and asked how to get the internet restored. After a few attempts the new customer service rep helping us decided to message the manager at the store, who was sitting right behind us. Who then unprofessionally discussed the issue rather loudly "that you just don't do that" and that was it. Never came over to discuss or try to help find a solution, did not even attempt to make it subtle. I asked if we could downgrade the service so we could go back to having the previous service, to which they said no and there was nothing they could do. At one point the customer service rep suggested I find another provider. It would have been nice to know before we changed the service that we would be losing the apartments' internet. They suggested I register the apartments as a separate property, so then Xfinity feels it is better for us to pay more property taxes than give us two boxes on the same property and charge for them on a bill? The space is used for working remotely which we can't do anymore and for overflow of family. I just felt this could have been handled better. It also really doesn't sit well when your management can't get up from the table and talk with customers and explain or help find a solution. You are the only provider in our area and I am stuck as to what I can do and I would have just liked a better discussion and better customer service. Not to mention as I looked at my updated bill you are still charging me for 2 gateways after the store explicitly told me I can only have 1 on a property!