Will diltiazem hcl 120 mg help pvc's and arrythmias if beta blockers don't?

Unsure: Beta blockers are usually the drug of choice in this situation. However, some venticular arrythmias doe respond to calcium blockers like verapamil. See a cardiologist for further evaluation.

Sometimes: These are two totally different classes of drugs and depending on the mechanism by which your pvcs arise, a calcium channel blocker may indeed be more effective. If drugs fail you, an expert center and electrophysiologist may be able to perform a PVC ablation to eliminate the beats from within the heart, but such procedures require a skilled electrophysiologist for the best chance at good results.