Your screenshots aren't showing correctly for some reason so the issue isn't really clear.
Are you trying to use cash credit on your account to buy a membership plan?
If so then as long as the cost of the plan is less than or equal to the amount of cash credit on your account then you should get the option to pay for the plan using your cash credit rather than your bank card at checkout.
Is that not happening?
Or are you getting some error when you try to pay that way?
If you have less cash credit on your account than the cost of the plan then you won't get the option to (part) pay using the cash credit.
If you need to contact 48 support about this then see the links in my signature below.
