Tree damaged by Comcast

Some time ago Comcast repaired a severed cable line on my property (line severed by contractor putting in new driveway for next door neighbor).  The repair included adding conduit which was not included when home was built.  In order to install conduit Comcast staff used a trench machine that went very close to our large redwood tree.  Some time later we noticed crown of redwood tree was dead/dying (orange).  We had an arborist come out and his opinion was that it was likely from root damage.  It has been several months since then and the dying portion of the tree has expanded significantly. (From top down).  I would like information on next steps to request financial assistance in having tree removed since the arborist believes the conduit install (and trenching through the roots) is the direct cause of the dying tree.  This is a very large tree (approx 100 ft tall).