Look for them under Tree Service in the Yellow Pages. Make sure they carry proper liability and workmen's compensation insurance before allowing them to start the job. Broken limbs should be removed. Generally, if the branch has not split away from the trunk, the broken segment should be removed back to the next major adjacent branch. Do not leave branch stubs.
Stubs encourage rot and decay.
For trees with tops broken out, remove the snags to the next major interior branch. Generally, this will be a major fork. Avoid topping the tree to allow small side branches to grow out and continue the tree's height growth. These branches will be weak and prone to breakage. To avoid stripping the healthy bark from the trunk when a heavy, broken limb is removed the 3-step procedure should be used.