Cloud service providers currently charge consumers for metered usage based on appropriate pricing model (fixed and spot pricing). When making reservations for cloud services in automatic pricing mechanism, consumers and providers need to establish Service-Level Agreements (SLAs) through Price and Time-slot Negotiations (PTNs). Whereas, it is essential for both a consumer and a provider to reach an agreement on the price of a service and when to use the service (i.e. time slot). Even though these issues are essential, mechanisms to automate the negotiation of price and time slot for cloud services using Quality of Service (QoS) have not been devised.