You can use your BA Amex to top up your Paypal Top up card and earn miles. That we know. Did you also know you can use your Paypal Top up card to pay off your BA Amex card ? Go to your Amex online account and click on 'make a payment' and enter your Paypal Top up card details as if it was a debit card. Might be worth posting this on page 1 as it doesnt mention it there !