Contact the seller, this is a user to user forum, your seller won't see your message.
If you don't hear from them or they refuse, file an item not as described case.
Recently I shipped a set of headphones to the buyer and forgot to include the adapter. The buyer was extremely polite and I apologized and mailed it out the next day.
Be polite and approach the problem professionally. If it escalates, you have the Money Back Guarantee to back you up.
