Monthly Charges for unreturned not refunding me despite returning equipment

I had unreturned equipment which I noticed I was charged for over 1 yr. Upon discovering this I returned the equipment in December and was told Xfinity would refund those fees. I moved and had unreturned equipment of $150 and this was returned last week and the $150 was credited. I am now being told the December equipment monthly fee they can only refund 4 months after I was told otherwise. Why did they not charge me $150 for that equipment? They would have refunded that like the equipment I just returned! Why can’t they refund the monthly charge? They should refund $150 or if fees charged to ete less they should refund that! I was never told of this fee. These fees were never told to me and when I returned the equipment was told something else. I need some understanding why not charge me $150 for the other equipment? Why can one fee be refunded and not the other. I am ready to cancel my new services! I can’t trust a company that sneaks fees without warning knowing customers dont review invoices specially when on autopay. They closed my ticket without a callback ECM0021196925