Quote: " This is our right"
No, it is not your right at all. You purchased a pack of models, your purchase included those models and only those models. If you want more models you buy another pack.
It's like going to a toy store and buying a puzzle, then a month later a new puzzle comes out, would you expect the new one for free? No you wouldn't.
The only updates to the mega packs you have a right to is if they change the system and the models don't work in GameGuru any more, then you can expect an update to make them work again.