Change a product 'Type'

Does anyone know how to sufccessfully change a product type for a listing (own brand lsting)?

I have tried uploading an Invenotry File and this changed the browse node category successfully but not the product type which I believe sets the referral fee category as well?

If I can't change it should I delete the listing and create a new one (no sales yet as new product and stock not in fulfilment centre yet). It is important as it is affecting the referral fee.