When an item is reported as being corrupt, and we process a refund, we do it in a way that notates the item. This informs the department that handles the quality of the iTunes Stores content, that there is an issue that needs to be addressed. That department then reviews the item in question, and contacts the content provider. iTunes then awaits the content providers update regarding the file. This process should have been addressed to you, at the very least you should have been advised that the item in question was being investigated.
Now when this happens we have very little information regarding the file itself. We are actually to be under the impression that the issues are download issues, not content issues, until the appropriate department reviews the content and states otherwise. As you can imagine, it takes a little while for iTunes to speak directly with the distributor regarding the issues, and then for the distributor to release the updated version. At that time, the fixed version is made available to all who purchased it. It is because of this, that apple does not immediately 'pull' the content from the store front, without giving the distributor a chance to address the issue. It is also due to this that we try to advise customers to give the item a few weeks to be fixed before attempting to repurchase.
With this being said, the item "Finding Nemo" has been notated. It will be reviewed shortly, if not already, and a fix will be made available as soon as the content developer addresses the issue.
I hope that this kind of explains what is happening with that file. I know it is not exactly what you were hoping to hear, but we really have to wait for the content developer to provide us a fix version, at least give them a chance to address the issue. As for a timeline on how long this should take, there is no exact number I can give, and we usually advise to give at least 3 weeks before attempting to repurchase.
I hope you have found this information helpful. I'd like to thank you for your continuing business with us at Apple.