[mozalina]

I want to ad %3 surcharge for any order which choose American Express as Credit Card.
The problem is in the second step of Checkout process we will ask for Payment option and when customer choose Credit Card they will go to 3rd step of Checkout, I want, if customer choose American Express then page be refresh and the "Order Total" shows extra %3 surcharge and it would be grate if we can show this surcharge amount as a separate line in the cart section and then the Order Total = Subtotal + Discount+ Shipping+Tax+ Surcharge(American Express).

I tried many ways but I couldn't figure it out how to make it by changing the templates, I think the logic is:

if card type == AMEX then
$cart.total_cost=1.03 X $cart.total_cost
Save this amount in database
refresh the page
show the new Order total plus the surcharge amount.

Is there any easier method to do this or can anybody please help me with that.
Many thanks.
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I am using 3.4.6