So were you selling Stubben leather work? If not then I don't see how you would have to refund them via paypal for calling dark brown havana! Esp when you also added that it meant dark brown :s
As has been said, it depends on the manufacturer. Stubben Havanna is a redy brown & chocco is dark brown. In many English makes Havanna is dark brown & then come a variety of other shades...Australian Nut, London Tan etc etc.