No you can't. S.75 of the Consumer Credit Act applies only where there is a direct link between the three parties - the credit card company, the buyer and the seller. The law states that the credit card company is jointly liable with the vendor.
In this sort of three party transaction, the credit card company does a 'chargeback' - gets the money back from the vendor where ever possible. They simply cannot do this if you have used PayPal.
When you use PayPal the credit card company has done exactly as instructed, paid PayPal the money, and PayPal have done as you instructed - paid a fourth party, the seller.
There is no direct relationship between the vendor and the credit card company.
If PayPal has received the money but not provided the service, you could invoke s.75, but that is the only time.