We had several players report missing cards from their Aether Revolt packs during the pre-release weekend. We contacted WOTC regarding this and received the following emails:
We appreciate you bringing this issue to our attention. You can rest assured that your report has been passed up to the appropriate teams for further review! Furthermore, your players are more than welcome to contact us at www.wizards.com/customerservice to start the product replacement process for any damaged cards they received. Please note, however, that we will be unable to provide replacement promotional foil cards as all prerelease materials are sent out to stores for the event itself.
Attn: Product Replacement
PO Box 707
Renton, WA 98057-0707
Plus, we’ll include something extra on the return to cover the shipping costs!
If they send it to us directly, they will need to include a letter with a full description of the issue, their first and last name, mailing address, phone number (with area code) and an email address for shipping purposes, or in case we need to contact them for any reason.