Based on what is stated online. If the product is not fit for purpose (even after being notched to fit the Panel Van) it will be law you get a refund.
Of course it can't be bodged or botched job in anyway. Ask for the refund and see what happens. ACCC and/or Consumer Affairs (or whatever they are called this week) will set them straight.

Imagine you purchase and install; then you or a passenger are overcome by fumes and this results in an accident or worse, even though you have install the seal and done everything to install as intended. It would only have to be proved a contributing factor and legal eagles would have them by the nuts.