Multiple things can cause this, I didn't bother to check your entire repository, so I'm going out on a limb here.
First off, you could be missing an annotation (@Service or @Component) from the implementation of
com.example.my.services.user.UserService, if you're using annotations for configuration. If you're using (only) xml, you're probably missing the <bean> -definition for the UserService-implementation.
If you're using annotations and the implementation is annotated correctly, check that the package where the implementation is located in is scanned (check your <context:component-scan base-package= -value).