Yes if your credit balance is equal to or greater than the cost of your plan.
In that case you should see the option to pay using your cash credit balance instead of your payment card at checkout time.
See here also:
What’s Credit?
Credit is the amount of funds that you can add to your My48 account with your payment card. Your credit will remain on your My48 account, and you can use this balance to pay for any additional cost that aren’t covered within your plan such as MMS, international calls, premium rate numbers and/or buying add ons.
The real sweetener is that you can purchase your plan from your available credit balance, so long as the balance covers your full plan cost.
Note that auto-renewal never uses cash credit and always charges the payment to your registered credit/debit card.
If you need to contact 48 support about this then see the links in my signature below.
