curl --request POST \
  --url https://docs.dezerx.com/api/application/services/{service}/downgrades \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "new_product_id": 123
}
'

{
  "data": {
    "service_id": 123,
    "invoice_id": 123,
    "job": "<string>"
  },
  "meta": {},
  "message": "<string>"
}