doTransaction API Call
The doTransaction SOAP call is used to action a type of transaction defined by the value in the transaction type parameter against a specified the PayU reference number.
If the setTransaction call sent through a transaction type that requires a follow up (RESERVE → FINALISE) then a doTransaction call needs to be done in order to complete the transaction.
Additionally, a doTransaction call can be done in order to CREDIT a PAYMENT done in the setTransaction.
In the case of a doTransaction for a FINALIZE. The transaction will go almost immediately from the NEW state to PROCESSING when PayU go off to the payment gateway to perform the payment. Upon receiving the response from the payment gateway the state is changed to SUCCESSFUL or FAILED.