Freight vendor is consistantly changing

Hello

Experts,

PO is created & against the condition FRB1 we have assign a vendor code. However GRN is also done, but freight invoice is came for different vendor against the PO.

Because this is the consistant process what we are doing is making the MIRO as per PO & through FI we make vendor to vendor transfer.

Is there any standard process available in SAP by which we can solve this problem.

Regards

Abhisekh Mandal