Apply an authorised part of a customer credit to a new bill

Records and local rule

Original customer C has confirmed usable credit 100 and new issued bill 300 in HKD. Customer instruction authorises using 60 on that bill, not all 100. Local policy requires same customer and currency and retains the unused credit. No new money receipt occurs.

Process the recorded case

1. Match customer and currency
2. Read exact authorised use
3. Record credit allocation to bill
4. Retain both remaining amounts

Another customer or currency needs its own decision; a shared contact or amount does not authorise transfer.

Check the outcome