The obvious comment here would be...

If you don't know where the wiring/plumbing is for your sprinkler system is,
how would the cable company know? Considering the size of the wiring, it
would be very easy to break a wire and not even know about it.

....and an even more obvious question is...

Did the cable company even do any digging on your property?

(Came late into the thread so forgive me if I missed something)