Amex Surchage - Not Warned - Buyer Beware

The other night i placed an order from PSA, and paid via Amex.
I got a confirmation email with the order as i expected.
The next day I got another invoice, but this time included in my order was an Amex Surchage of 3%. Sure enough, my grand total had changed, with the surchage added on.

Now i know the surcharge is not massive, but the fact was that i was NOT warned about this surcharge. No where on the site does it mention this surchage, and when i selected to pay with Amex it did not warn me.

So, just a heads up to all potential buyers - DO NOT PAY WITH AMEX (if you dont want to pay extra)!

On a positive note, i was informed my order had been shipped the next day.