If your customer wants to use an additional service in the form of a component, you can simply add it to his subscription using the web UI. Go to the desired contract by navigating to the "Customers" tab, searching for the customer and clicking the "Contract-ID".
Go to the "Component Subscriptions" tab in the contract details. If the customer wants to increase or decrease a component that has already been posted, you can adjust the quantity using the menu.
In the "Change Component" window you can enter the desired quantity, an optional description and the date from which the change is valid. If you set the change date of the adjustment before the next billing date, a credit memo is created for the components already paid for a new invoice is created for the new number of components. If the change date is equal to the next billing date, no credit memo is created for the components paid for and the customer receives an invoice for the new number of components in the next billing period.
If you want to add a new component, select the component from the selection menu, set the start date and optionally add a description. Then click on "Add".
The component has now been successfully added to the contract and will be billed in the next billing period.