As Swish Embassy is based in Canada, we are unable to process the Discover Card directly as they are primarily a US card not widely used in other countries.
PayPal Workaround
If you wish to pay with your Discover Card, you may do so by checking out with PayPal.
You are not required to sign-up for a PayPal account. Simply click on "Pay with Debit or Credit Card" as highlighted below.