MC50 promo code for $50 virtual MasterCard

In the process yesterday of signing up for the 5-year1 gig Xfinity internet promo, I got a pop-up window saying to use code MC50 for a $50 virtual MasterCard (to "sweeten the deal" it said).  I struggled to find where to insert it and ultimately clicked through to place my order without the MC50 code.  I retraced my steps today and see there is a place to put the code in the checkout process. I took a picture of the pop-up.  I tried phone support today and the CSR "Chris" was clueless telling me first I couldn't pay for my monthly bill with a gift card and then that it was for referring another customer to sign up for Xfinity.  He finally just told me I'd receive the card and didn't have to do anything.  i think that was just to get rid of me and in fact he disconnected the call without resolution.  I have my order and account numbers.  Can you manually add the code to my order?