iSupplier, how do I "Shut it Down"?

I may be in a different situation from most.

     We are a shared financial services group. Purchase orders get created in the manufacturer ERP and get interfaced to us. At the same time the manufacturing ERP also sends out the PO to the supplier. From there a supplier send us the Invoice and we cut the check for that invoice and maintain the GL entries.

     This is causing our suppliers issues because the PO number that they send to the supplier is different from the PO number sent to Oracle. As a result we are getting double ordered for some of our suppliers. Suddenly this has got raised to higher management as a serious issue and got dumped in my lap.