1. A method comprising: receiving, at a server computer from a client computer over a network, a single order initiated by a consumer at a single web site detached from payment processing capability, wherein the single order is associated with a first set of products and a second set of products, the first set of products and the second set of products offered by a first merchant associated with a first merchant identifier and a second merchant associated with a second merchant identifier, respectively, wherein the first set of products and the second set of products are offered to the consumer at the single web site; extracting, by the server computer from the single order, a first payment account identifier for a first funding source associated with the consumer, the first merchant identifier, the second merchant identifier, a first amount for a first payment transaction for the first set of products offered by the first merchant, and a second amount for a second payment transaction for the second set of products offered by the second merchant; generating, by the server computer, a first authorization request message for the first payment transaction, the first authorization request message comprising the first amount and the first merchant identifier; transmitting, by the server computer, the first authorization request message to a first issuer computer associated with the first funding source, wherein the first issuer computer is configured to enable payment of the first amount to the first merchant directly from the first funding source associated with the consumer; receiving, by the server computer, a first authorization response message from the first issuer computer, the first authorization response message indicating whether the first payment transaction is declined by the first issuer computer; generating, by the server computer, a second authorization request message for the second payment transaction, the second authorization request message comprising the second amount and the second merchant identifier; transmitting, by the server computer, the second authorization request message to the first issuer computer, wherein the first issuer computer is further configured to enable payment of the second amount to the second merchant directly from the first funding source associated with the consumer; receiving, by the server computer, a second authorization response message from the first issuer computer, the second authorization response message indicating whether the second payment transaction is declined by the first issuer computer; determining, by the server computer from the first authorization response message and the second authorization message, that only one of the first payment transaction or the second payment transaction is approved; upon determining that only one of the first payment transaction or the second payment transaction is approved, generating, by the server computer, an order interrupt message indicating a declined payment transaction based on which of the first payment transaction or the second payment transaction is declined; and transmitting, by the server computer, the order interrupt message to the client computer.