X1 DVR set top box broken, how do I get it replaced

Hello,

I have 4 TV's, my familyroom has the X1 DVR set top box and bedrooms have the small boxes. the X1 DVR set top box is humming, wont rewind amoung other things, it says card is removed.  I have not removed anything so I think it just stopped working, how do I get a new DVR?

Thank You