You mean you can't use cash credit on your account to buy your plan?
You should get the option to pay using your cash credit at checkout time if the amount of cash credit on your account is greater than or equal to the cost of your plan.
See here:
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.
How much cash credit is on your account and what is the cost of your plan?
If your cash credit balance is less than the cost of your plan then you'll need to add more cash credit before you can use your cash credit balance to buy your plan.
If your cash credit balance is equal to or greater than the cost of your plan but you're not getting the option to use it to pay for your plan at checkout time then you'll need to contact 48 support for assistance.
See the links in my signature below.
