curl --request POST \
  --url https://whitebit.com/api/v4/main-account/smart-flex/investments/payment-history \
  --header 'Content-Type: application/json' \
  --header 'X-TXC-APIKEY: <api-key>' \
  --data '
{
  "limit": 50,
  "offset": 0,
  "plan": "8f2e9d3c-1a4b-4c2d-9e5f-6a7b8c9d0e1f",
  "investment": "inv_123",
  "transaction": "tx_456",
  "dateFrom": 1640995200,
  "dateTo": 1641081600,
  "request": "{{request}}",
  "nonce": "{{nonce}}"
}
'

{
  "data": [
    {
      "createdAt": 1640995200,
      "planId": "8f2e9d3c-1a4b-4c2d-9e5f-6a7b8c9d0e1f",
      "investmentId": "inv_7e2d9c3b-1a4b-4c2d-9e5f-6a7b8c9d0e1f",
      "currency": "USDT",
      "amount": "15.75",
      "transactionId": "tx_9f3e0d4c-2b5c-4d3e-8f6g-7a8b9c0d1e2f",
      "actionType": 4
    }
  ],
  "limit": 50,
  "offset": 0
}