Currently if you are capturing a pre-auth payment via the Wordpress Dashboard, it will only capture the full amount.
However on certain products there are times when the price changes so the store may pre-auth an amount of €100 but when the it comes to capturing the payment, only €90 of that amount is needed.
Currently you need to go through the AuthiPay dashboard to manage this type of a scenario, but it would be great if this can also be handled in the Wordpress/WooCommerce dashboard.