Got charged for an xfi pod I never requested, worried if they deny my refund request I'll have to prove that I didn't order something.

OK, full story here is I moved into my new place and started a remote job back in July. At the beginning of that same month, I started my xfinity internet service. By August I realized that with the only wall connection being on the bottom floor of a 3-story townhome, my internet was not going to keep up with the remote work/all the devices needing connection. Before the end of August, I spoke with an xfinity rep who told me I did not qualify for a free Xfi pod with my unlimited plan, but I could purchase one for $119. After complaining that I absolutely should not have to pay full price for a pod when my very large plan should be sufficient to at least reach my office on the 2nd floor, they agreed to only charge me half price. Anyways, I got my 1 xfi pod and all of this is reflected accurately in my bill.

Where it gets into funny business is when I went to switch to AT&T fiber and noticed that for the month of October, I was charged $140 more than my normal plan! When I spoke to a rep, they told me I had purchased another xfi pod from them and tried to tell me that their xfi pod 2nd gen models cost $250. Now clearly he didn't check anything about the price of the pods or my bill because in no world do they cost that much, they are $119 on the website, clear as day. Even 2 of them are $199. It was clearly my bill with whatever charge on top of it. 

I have requested a refund for the difference between my bill and all that extra charge (which btw, factoring in sales tax by my zip code is still MORE THAN AN XFI POD), but find myself worried that since it's a "refund request" that they will find some reason not to process the refund. This is based on a history of sheisty practices from similar experiences with service providers. What I want to know is whether I'm an isolated case and this was truly an accident or if there are more out there who have had this happen to them and if they've needed to provide some type of proof that they DIDN'T order something. I wouldn't know where to begin on that but absolutely no way I'm letting myself be accountable for a $130 over my bill without a valid explanation.