Xfinity Flex Box Charges

I am seeking billing help for the charges for 2x Xfinity flex boxes I have been billed for.  When I changed my service plan about a year ago, the associate advised I could get an Xfinity flex box for free with my plan.  I only received 1 Flexbox.  I have been getting billed for 2 boxes since the billing cycle of 04/02-05/01 2022 till now.  Looks like that would add up to $200 in extra charges that should not have been applied to my account.  Please assist in getting these charges refunded.  Appreciate the help!