"It seems Asus will have nothing to do with purchases made through Amazon for reasons not explained. I sent off the device in the original box two weeks later I receive an invoice from Asus (albeit their repairs sub-contractor) for £40!! They found no fault and I will have to pay £40 for the device to be returned"
This is one of the problems when purchasing through a third party, not recognised by a manufacturer as being one of their approved retail seller's.
Is the item still faulty and requires further action, or are you seeking your £40.00 back?.