Most codes are written for a first order: they give a new customer a discount and set a minimum basket. Several codes can sit on this page at once, yet the discount is still granted once, so try them and keep the one that lowers your total the most.
One detail matters: the codes work in the Bellissimo Pizza app, not in an order placed on the website. Install the app, register with your phone number and paste the code into the field on the payment screen. Check that the discount has been counted before you confirm the order.
Bellissimo publishes neither the terms of these campaigns nor their end dates on its website, so the app is what shows the exact condition. That is why each code page states plainly what we know and what we do not. Offers from other restaurants and shops sit in the food and delivery section.