No Receipt No repair

We have a mobile wifi device that we purchased on contract with Telkom. The device display became defective and my wife went to take it in for repairs. The person that assisted my wife, mentioned to her that we need a receipt. Anyway my wife mentioned that she was unable to find the receipt and the assistant looked on their system and found the purchase, however the person that sold us the device did not capture the receipt number on their system.<br> Now Telkom says that we need the receipt to have the Device fixed. How can it be our fault if the staff cannot do their job and then we are inconvenienced. We paying the contract and we are unable to use the data at the device has become defective.