curl --request POST \
  --url https://api.topsort.com/public/v1/billing-service/vendors/{external-vendor-id}/balance \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "balance": 123,
  "description": "Free credits added to the account"
}
'

{
  "result": true
}