How to get a simplecart order moving

There was an order placed in a client simplecart store, for some reason this user did complete payment at authorize but didn’t land back on the site to complete checkout… The client has payment and wanted to get the order moving, I inquired of support and was told to update the order status to processing and did so, but it sounds like it is just sitting there with a status of processing but isn’t actually continuing on its progress as if payment was received and the user returned back to the checkout page. Any help? Thanks.