Our supplier has provided us with stock, these have been invoiced at the incorrect price. Do we record the products into Infusion?
Yes, record the receipt and invoice as they have been supplied.
Then create a Purchase Order with the Product codes recorded as Negative quantities and in the Notes box refer to the Invoice and why you are asking for a credit.
Return this to your Supplier.
When the Credit arrives back receipt the Credit and add the Product code with the positive quantity and the difference will be the value of the Credit. Process as usual.