Potassium permanganate and water used as a footsoak works wonders.

Use enough KMNO4 (potassium permanganate powder availible off the internet) so that the foot bath solution is a dark purple.

Place your feet in the solution ant let them soak for at least 30 minutes. You want it to soak into the dense callous like the heel area.

Be advised: It will stain your toenails chocolate brown! as well as deep callous areas! So don't freak out.

Do the foot soak every week for 3 weeks. It works like magic.