That is frustrating experience. I don't know if they will help, but you might try posting your request at Customer Service - Xfinity Help and Support Forums. Good luck!I went on the Xfinity forum to find out (a) which model DVR I needed to display 4K and (b) whether I needed to make an appointment at the store to exchange DVRs.
I learned the box I wanted was XG1v4. I learned I should make an appointment. I spoke with a phone rep who assured me my nearest Xfinity store had XG1v4s stacked and waiting to go. I made an appointment for today. I disconnected my old box and drove 40 minutes to the nearest store.
My appointment meant nothing. I waited in line behind old-timers wanting to pay their bills in person and a woman who wanted a lesson in connecting her cable box.
I finally get seen. The guy says he doesn't think they have any XG1v4s but he'll look. 10 minutes later he returns with a box. Another of the same box I brought in to exchange, nicely shrink wrapped. He explains the XG1v4 has been discontinued and there will be no more 4K DVRs from Comcast ever again.
I am not experiencing Awesome.