If your card declined, select pay with PayPal at the checkout. You can then select "Pay with card". It should work this time. Gift cards are also accepted.
Step 1.
Select PayPal in the payment method section then click the complete order button.
Step 2.
You will then be taken to the pay with PayPal page. Underneath the login, section click the "Pay with a card" button. 
Step 3.
Complete your details on the PayPal guest checkout to complete your order.
If by any chance this does not also work, you would need to contact your bank to authorise the purchase or for further assistance email: support@fitaffinity.com