Does anyone know the official rules for Destruct 3?
This might help. Although it's only a review, it does explain a lot about the scoring and building rules. There obviously are a few rules that are missing (ie. how the dice work).

I assume you do not have any kind of shop receipt for the game. You could suggest to them that you could send them a picture of the game to prove you actually have it. They could describe a specific setup for you to replicate so you can't just pick a picture off the web.