💡 Also, you should know...

If the request includes neither a amount nor a tip, the system marks the transaction for settlement with no changes in the amount fields.
If the request includes a amount but no tip, the system marks the transaction for settlement with total amount as the Amount and the tip as zero.
If the request includes both a amount and a tip, the system changes the respective amount and marks the transaction for settlement.
If the transaction is already settled or otherwise not eligible for modification, EdgePay declines the request with the error message Modification not allowed.

🔖 Adjust Sample Payload

var request = require('request');
var options = {
  'method': 'POST',
  'url': 'https://api.edgepay-uat.com/payment',
  'headers': {
    'Content-Type': 'application/json',
    'merchantKey': 'E3DFE3D0150EB516F4E351CE7FE5A2FB799B320BDC5D523B',
    'externalReferenceID': '1234561688596045',
    'transactionDate': '2023-07-05T21:59:01'
  },
  body: JSON.stringify({
    "adjust": "yes",
    "merchantID": "6320340123456900",
    "terminalID": "88800000282601",
    "transactionID": "CS97032954537318927",
    "amount": "1.00",
    "tax": "0.01",
    "tip": "0.02"
  })

};
request(options, function (error, response) {
  if (error) throw new Error(error);
  console.log(response.body);
});

{
    "result": "A",
    "responseCode": "A0000",
    "responseMessage": "Success",
    "merchantID": "6320340123456900",
    "terminalID": "88800000282601",
    "timestamp": "2023-07-05-14-52-01",
    "securityResult": "D",
    "securityMessage": "DECLINE",
    "authCode": "TAS405",
    "processor": "TSYS",
    "amount": "1.00",
    "tokenID": "5840938697279316",
    "transactionID": "CS97032954537318927",
    "originalTransactionId": "CS97032954537318927",
    "invalidEffectiveDate": false
}

☑️
Authentication Header:

merchantKey = this is the API KEY 🔑 that is associated with your MID provided by GETTRX.

externalReferenceId = It is a unique record identifier. Combination of 123456 + UNIX timestamp Sample: 1234561687543122

transacationDate = Set to UTC timezone 🕑
                 Format: YYYY-MM-DDTHH:MM:SS