Credit card protection falls under s.75 of the Consumer Credit Act which gives equal liability to the credit card company when goods are purchased using the credit card.
However, this applies to third party transactions - the buyer, the seller and the credit card company.
Your scenario does not fall in to this category - you authorised your credit card to pay x amount to paypal so paypal could forward the money to your seller.
Your credit card company did as instructed and there was nothing wrong at all with that transaction.
Some credit card companies voluntarily give refunds in 4 party transactions such as PayPal - look at your terms and conditions.
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