curl --request GET \
  --url https://api.comm.com/api/v1/billing/top-up \
  --header 'Authorization: Bearer <token>'

{
  "data": {
    "enabled": "<string>",
    "threshold": 123,
    "amount": "<string>",
    "reference": "<string>",
    "payment_method": "<string>",
    "created_at": "2023-11-07T05:31:56Z",
    "balance": "<string>",
    "balance_number": 123
  }
}