Hi @Add_87708 and welcome to 3Community 😊
I'd love to help you with this, do you know what plan you are on? If you're not sure login to your My3 account and you'll see your plan name on the dashboard. If you're not sure where to find it have a look at our blog All about: My3 and Prepay.
If your plan is 3 Prepay 15, 20 or 30 these are draw-down plans. What this means is if you're on 3 Prepay 20 and you top up by €20 this amount is automatically drawn down and your plan is activated.