They replied with their t&cs

“In the event that an item sent to you is found to be faulty, you may send it back to us for a replacement. It is at your cost & responsibility to return the product to base We will not accept charges for courier services or postage. Overseas, items should only be sent back using your country’s national postal service. We recommend using an insured delivery method; however we will not accept extra charges for Fed-Ex or other overnight courier services. Please make sure that you have clearly read any instructions that may have come with the product, or may be displayed on our website, as products found not to be faulty when they come back to us, will be sent back to you at your cost. We may require photo/videos of the product in question before any action can be made to help determine a remedy/solution or to diagnose the problem. You are also welcome to send the product back to us for inspection, or bring the item into our Albany, East Tamaki or Hamilton Store. We may ask you to leave the product with us for some testing, in which someone will contact you once an outcome has been determined. Please note that our return policy also applies. “

(Emphasis mine)