Dev:Gateway:MerchantParamsRefund
From WHMCS Documentation
| Key | Sample Data | Description | 
| Standard Parameters | ||
|---|---|---|
| companyname | WHMCS Limited | The company name set for the WHMCS install | 
| systemurl | http://www.domain.com/whmcs/ | The URL to the WHMCS installation | 
| invoiceid | 123 | The invoice ID | 
| description | Company Name - Invoice #123 | Invoice text representation | 
| amount | 19.95 | The amount due | 
| currency | USD | The currency of the invoice | 
| clientdetails | Array | An array of the clients profile data (firstname, lastname, companyname, address1, address2, city, state, postcode, country, phonenumber, email) | 
| Refund Specific Parameters | ||
| transid | ABC123 | The original transaction ID the refund is to be issued against | 
| cardtype | Visa | The card type | 
| cardnum | 4222222222222 | The card number | 
| cardexp | 0514 | Card expiry date (MMYY) | 
| cardstart | 0508 | Card start date - if provided (MMYY) | 
| cardissuenum | 1234 | Card issue number - if provided | 
| cccvv | 123 | Credit card verification value (first transaction only) | 
| gatewayid | xxxxxx | Gateway token value if stored |