Namhost uses Peach Payments to process credit card payments. Peach Payments supports credit cards and many debit cards.
To pay by credit card, simply click on the link in the invoice email that was sent to you.
The e-mail should contain the invoice and the link opens it in your Internet browser. Once the invoice is open you can easily select "Credit Card / Debit Card" at the top left corner and then proceed to pay by Credit Card / Debit Card.