Once a Purchase Shipment is Updated (ie: Closed) you are unabe to re-open it change it or reverse it through the shipment screen. The process for reversing it is as follows:
1) Determine the Purchase Receipt Batch Number(s) generated from the orginal Purchase Shipment by taking note of the Puchase Orders involved.
2) Find these on the Purchase Receipts Batchs List screen (tick, include updated Status) (Customise the Purchase Receipt List to include the PO # and search on this)
3) Open each Batch and press the 'Un-Post All Purchase Receipt Entries' button (All landing charges and receipts for this Purchase Receipt Batch will be reversed.)
4) From the List grid delete the Purchase Receipt batch (NB: If a Purchase Invoice has already been created and / or posted, you will need to delete that first before deleting the Receipt)
5) Repeat Steps 3 and 4 for all other Purchase Receipt batches that were on the Shipment
6) Create a completley new Purchase Shipment and process as usual with the landed charges