@fify-- You should see your podiatrist and ask for a recommendation.
I got my callus ointment from my podiatrist's office but it's a product that's available without prescription on the market. I don't want to sound like I'm advertising a brand, so just ask your podiatrist or a pharmacist and they'll know. It's one of the best callus treatments on the market.
The ingredients are actually very simple. It just has enzymes, petroleum jelly and camphor. The enzymes break down the callus, petroleum jelly protects skin and camphor relieves pain and inflammation.
My calluses started disappearing from the first week of using this product and they were completely gone by week three.