You can definitely use it while making an online payment. However,in case you have opted for Card On Delivery option, you will not be able to use your AMEX card for the payment.
Zefo Service Partner Warranty covers issues occurring due to manufacturing/material defects. It though does not cover existing defects, or damages caused by the usage of the product beyond its intended use and wear & tear in the natural course of product usage.
In such extreme cases where the amount is deducted but the orders are not placed, the amount will automatically be refunded to your account within 5-7 working days.Please contact your Bank for the same.