Top up
Top up when the value is already in front of you, not before. Below zero is allowed and nothing is blocked.
No money moves here yet. This site has no payment link of its own, so the top-up below is the meter's simulated cart, which says it is simulated. When the lead adds a payment link, this page sends you to it instead. What needs a human says what is waiting.
Back to your account. A payment, once there is a link, returns to the topped-up page, which adds the credit once per payment.