I'm a little nervous because some of my boots that used to be simply close-fitting are suddenly very tight at the top of the calf, like to the point where I'm afraid the zipper might not go all the way up.

I know some of you have had boots stretched by cobblers, but the only professional shoe repair service I have ever had is to get my heels re-tipped.

How much can (or should) they get stretched? Can they stretch them in a single spot, such as the top of the calf, so I don't end up with incredibly baggy ankles? Are there certain kinds of leather that are stretchable, and others that aren't? What should I expect so far as cost? Can any cobber do this, or should I take my boots to a specialist (Nordstrom flagship? Or the manufacturer, since one of the pairs are Clarks boots?)