Canada 1938 Montreal to Hawera New Zealand short paid postal dues reverse cover

Canada 1938 Montreal [SP12 38] addressed to Hawera New Zealand.

Canada airmail 6 cent stamp applied ,short paid ,threepence double defficient postage.

Reverse shows  a strip of three New Zealand Postage dues applied and Hawera RCDS 1 oct 1938 cancel flap open so the cancel is partially affected ,two other Hawera double ring cancels applied same day .