For items which are under warranty any defects in the goods which under proper use appear within a reasonable period after delivery and which are due to faulty materials, workmanship or design will be made good by us either by replacement or refund. Any claim for goods or the defective parts should be returned together with proof of purchase and (if relevant), all complete accessories, instruction manuals and software and, wherever possible, in the original packaging. Any claim for defective goods or parts must be made in writing (specifying the date of purchase and invoice number) within a reasonable period of time after delivery.