Abstract: A reverse dutch auction processing method executed by a computer server and computer programs thereof; A user sends a request including at least a value for a parameter representative of a property of the product or service and a maximum first acceptance time period for a product or a service to potential providers; the potential providers receiving the request, wherein in case of acceptance of the request by at least one of the potential providers within said maximum first acceptance time period, closing the request upon confirmation by the user, and in case of no acceptance of the request by any of the providers indicating, by at least one of the providers, an alternative minimum value for the parameter of the requested product or service within or after the maximum first acceptance time period, the user confirming the alternative minimum value by calculating at least a temporary probability of acceptance.