This API is used to extend the expiry date of a valid link. A valid link is one that isn't expired or a link for which the transaction is in a pending state.
For the list of error messages and their description that you may encounter when Smart Send APIs integration, refer to Smart Send Error Codes.
The pid is payoutMerchantId, however it is different from the PayU merchant id. Check the Payouts Dashboard or call the PayU Customer Support if you don’t know your payoutsMerchantID.
For sample request and response, refer to Sample Request and Response for Smart Send APIs.