You did not indicate the nature of Paypals response-i.e. was it charged back because of a stolen credit card that was used. Was it a dispute by the cardholder. This may be late, but if you have a physical address that this was delivered to and the nature of the complaint was a stolen credit card that physical address is a great lead for investigation, whomever is at that physical address, or was dumb enough to let someone use their physical address, knows who used the presumably stolen credit card.

If the chargeback was because of a complaint by the cardholder to the cardhoders credit card company, about quality of merchandise, or delivery, you get to put in your side of the story. You did not say what the nature of the complaint was. The question lacks specific details. Paypal has a procedure for disputes, and you never mention what the nature of the complaint was unless I missed something here.

When a Cr. crd co. disallows a charge, the merchant gets to put their two cents in too. One other thing you have the phone number of the order person and said you spoke to them, have you not tried calling that phone num, and finding out if someone disputed. It seems you may have just lied down and took it on the chin, you have to fight back here, that phone number is also a good source of getting to the bottome of this "chargeback"