Poor Customer Service

I purchased a property last year October 2021 that has a Defy Oven and stove. The previous owners immigrated. The oven is stopped working I emailed Defy and they are unwilling to verify if the oven is under warranty or not because I do not have an invoice. A lady named Gladys Malebye responded stating the following "Unfortunately without the invoice the call will have to be booked as a cash call" I informed Defy, that if the oven is not under warranty, I am more than willing to pay for the repairs. I feel that this is bad practice. Since when does one have to request invoices for stoves, ovens and hobs that form part of a property purchase.

Awaiting their response...