What you are dealing with is that Windows-1252 usually claims to be ISO-8859-1 Latin-1, but it really isn't. There is a small section - like sixteen code points or so - that Microsoft has decided to use for characters like typographic quotation marks (aka. "smart quotes") instead.
My best guess is that your transfer software (either by configuration or developer's decision) assumes that Win-1252 is equal to ISO-8859-1. Fix that (if possible) and you fix the problem.