This is a well-known problem with cars that use a handbrake that acts on the pads, rather than having a separate little drum with its own shoes. I believe the Citroen Xantia was notorious for rolling away. The method of stepping fairly hard on the footbrake while pulling on the handbrake seems to work best for me. Honda obviously acknowledge this problem because the owners' manual (page 297) advises that the transmission should be in 1st gear with the front wheels turned away from the curb (I think they mean kerb!) if parking facing uphill, and in reverse gear with the wheels turned towards the kerb if parking facing downhill. I guess it's a case of Honda misguidedly changing things for the sake of it, just as they changed the wonderful CVT transmission to the dreadful i-Shift, and then changed it back again when there was an outcry. My old 2003 SE had drum brakes on the back (perfectly adequate for a car of this type) and of course the handbrake worked fine. I wouldn't be surprised if the Jazz soon reverts to drum brakes on the back, or at least a separate handbrake drum with its own pads built into the rear discs.