Bud, just go through your transaction history and find your payment.
You will need the transaction code of the payment, some rdiculoous 20 something didgit long number that if full of numeric and alhanumeric digits. Copy and paste works well.
Then you go to like, lodge a complaint or something like that.
Paste that code in.
Then it will say, are your sure? etc etc
Then you will be able to communicate with the seller about it, saying your haven't received it etc etc
Once you are done talking, and have had enough of it.
You can lodge to a full claim and Paypal will investigate.