3 hours ago
2 hours ago - last edited 2 hours ago
And?
What's the problem?
If you have at least €3 cash credit on your account then you should get the option to use it to pay for the add-on at checkout time.
If you are habitually running out of mobile data then you might want to consider switching to the unlimited mobile data €12.99 plan.
If you need to contact 48 support about this then see the links in my signature below.