A callus is caused by too much pressure on an area. There is no 'plasters' or medications that can take away pressure. A Podiatrists can easily remove a callus by debriding it, but unless the pressure that caused it is removed, its going to be an ongoing problem. If your stilettos caused the pressure, then you simply need to stop wearing them. If not, then I suggest you get to a podiatrist to see if there are any other options to get the pressure off, such as off loading padding or something like that.