I doubt you've been hacked.
If the site you purchased the goods from was secure (HTTPS:/), your details would have been encrypted before they left your PC.
It's more likely that a dishonest employee has used your details to make a purchase.
When you purchase online you give the trader all the necessary information required to make the purchase, name, address, card number etc.
It would be easey for anybody with access to All of your details to impersonate you and make a purchase in your name.