This is a tough situation with no easy answer. On the one hand, we don't know if the administration is ignoring teacher referrals, we just know that whatever discipline strategies or consequences the administration applies (if any) aren't working. On the other hand, there is obviously a problem at the school, at least from your family's point of view. Several suggestions come to mind:
-Try starting by making an appointment with the principal. Don't frame the conversation as a complaint about what campus administrators are/aren't doing; share some of what your child has shared with you and use the last sentence of your post as a way to start the conversation..."I don't want these issues to continue ... what can we do / how can I help make things better?"
-If the climate at the campus level isn't conducive to starting with the principal, see if there is someone at the administration building / central office who can help. Again, you'll want to make an appointment with someone to share your concerns and let them know about a situation on XYZ campus that they may not be aware of.
-If informal steps don't work, there is probably a formal complaint process for parents; look into how to utilize it, what the guidelines are, etc.
-Get involved in the PTA or other parent/teacher organization. There is always strength in numbers; if other parents share your concerns, meet with the principal as a group to come up with ways the PTA can help with student discipline (donate good behavior incentive prizes, make behavior charts for each classroom ... it all depends on what grade level we're talking about).
Disruptive students definitely have an impact on teachers' teaching and students' learning - both the disruptive student's and that of the 'innocent bystanders.' Whatever you are able to do to correct the situation will not only benefit your child, but you'll be making the school a better place for the rest of the students and their teachers, too. Good luck to you!