Clssifieds Plugin: Archive Title Translation

We've started translating your plugin using the .po .mo files and we have just on small problem.
When in classifieds Archive, the page title begins with "Classified Category:". We couldn't translate this using the .mo files. We thought that the title is constructed by using the taxonomy's single name label. We 've tried changing the label through custompress but that messed up all the classifieds archives.
Is there any other way to translate this string?