Your post was blank @Jamesmcl1797 and the subject line doesn't really explain your issue in enough detail to offer useful advice.
If you want assistance from the Community Forum then you need to explain/describe your issue clearly and in detail.
What membership plan are you on?
The €12.99 plan comes with unlimited Irish mobile data so you can't run out.
Are you on one of the cheaper legacy plans with a limited mobile data allowance and you've used it up?
In that case you need to buy a mobile data add-on if you want to continue using mobile data to the end of the membership plan month.
Or is the issue something else?
What exactly do you mean by "cannot top up"?
What are you trying to buy and what happens when you try?
Any error messages?
If you need to contact 48 support about this then see the links in my signature below.
