Hello there Dartchump,
Than you for your post and welcome to the community!
In general, if you see an unauthorised charge on your PayPal account, you can report it directly from your Resolution Centre. You can find the instructions on how to report unauthorised activity here.
If this is what happened, you should change your password and security questions to restore the safety of your account. You can do it from the settings of your PayPal Profile by clicking on the 'Security' section.
Before disputing the payment, though, if you have already had payments completed to the same seller in the past, my suggestion is to check if you have initiated a billing agreement or a subscription with the seller. You can find this option in the 'Payments' section of your settings.
I hope this helps!
Martina
