Bargain! 😮 I take it most of that is the labour?
In this case, a new engine was fitted, so if the cam cover is faulty, it should be replaced under warranty. It's possible that it was tightened out of sequence which caused it to warp and then crack. For the sake of warranty claim, don't tell them that you've tightened any of the bolts, as they could say you've over-tightened it to get out of the warranty payment.