Order a free SIM Activate your 48 SIM
You mean can you buy membership with your cash credit balance on your account?
Yes. Just topup your cash credit balance if necessary:
How do I top up? Overview of the top-up payment op..
You can check your cash credit balance online or by short code:
You can do this by logging onto you online account, going through the normal membership purchase process (https://www.48months.ie/membershop?cat=memberships) and at the end choosing to pay with your cash credit balance rather than your card.
Alternatively you can buy membership by text and it will be charged to your cash credit balance:
How do I buy stuff by text?
Hope this helps.