Determine if the UnionPay Pre-Authorization transaction you wish to complete was assisted or not by looking at the Pre-Auth receipt. If UNIONPAY is printed under APPROVED, then the transaction was assisted. Proceed as follows:
If the original UnionPay Pre-Authorization was not assisted, then perform an Advice as you normally would.
If the original UnionPay Pre-Authorization was assisted, then start an assisted UnionPay transaction for Pre-Auth Advice and follow the prompts on screen. If needed, refer to the Advice transaction and to the additional prompts for UnionPay cards.