Hi InsiteWA - thanks for the question!
Just process a negative pay for the overpaid amount. This involves replicating the amounts from the original pay, but change the positives to negatives, and any negatives to positives. Don't forget to change the accrued leave entitlements too. The net pay should then match the original pay, but as a negative amount.
This will reduce that employee's YTD amounts and you can match the deposit in the bank account with the negative pay transaction.
You can then process the pay again for the correct employee.
I hope this helps!
Adrian