sewer line damage by Comcast installation

when Comcast installed their cable they drove a metal rod through our sewage line. we have had multiple back ups and the water company finally put in a camera which identified what is causing the back ups...the metal rod that i assume is ground for the cable extender box in our front yard. Who do i contact to have the problem repaired. I have already spent $1250  in just the past month clearing out back ups caused by the rod.  Thank you. Wayne [Edited: "Personal Information"]