I think if you could send a few of us some pictures individually (since there is a restriction?) a determination might be made on it's repair. I don't own a Taigen tank but a tank is a tank and have built many kits and modified RTR's and should be able to help tell if it is severe or not. Small parts can be attached fairly easily but the damage with the turret sounds like there might be a structural issue hidden from plain sight and if the vendor would work with you, send those parts affected.

This is a great opportunity to experience just how the tank went together without risking another possibility of damage occurring once again by returning it and waiting on another, which doesn't sound like it's all the vendors fault. The heavier an item is the better chances it will become damaged IF it's not packaged right or handled.