curl --request POST \
  --url https://api.altera.co/sales/markUnpaid \
  --header 'Authorization: <api-key>' \
  --header 'Content-Type: application/json' \
  --data '{
  "invoiceIds": [
    123
  ]
}'

{
  "result": "OK",
  "data": {
    "invoiceId": 12413
  }
}