No resolution to multiple in warranty service requests

I have still not received communication from a technician nor have we had any resolution to our protracted issues and repeated service requests with our in warranty DDW240 dishwasher. Our service requests have been "escalated" twice since we first logged a report on 27 January, and our third service request is still awaiting the technician's response or communication despite repeated escalations and followups with Defy. It has been 8 working days since we were allocated our third job number (***6), which is not only a whole week longer than Defy's "turnaround time" (as per their service centre), but more importantly, it is the third service request for this unit alone.

But there still seems to be very little urgency to repair or replace this unusable dishwasher. The technician has yet to respond or communicate, despite our followups to Defy and escalations from Defy service representatives. Moreover, it has been over 6 weeks (a month and a half) since we first reported the problems. But most significantly, the dishwasher has already been inspected and "repaired" by a technician twice (Job numbers ***6 and ***8). The unit has already had both its motor and its PC board replaced, and yet it is still not working.

As such, we are not sure why we are being made to wait for an unresponsive technician to come a third time. He knows what the problems are and he has not fixed them, despite two previous attempts. At what point does Defy accept that they have a defective unit that is still under warranty?

We have paid for a working Defy appliance, which Defy's website notes as having "unparalleled performance and reliability". But we have not had this Defy reliability nor any "performance" since 27 January (despite two inspections, two repairs and three service requests).

To be clear, after the extended delays and ineffective attempts at repairs, we would appreciate this matter receiving your urgent attention and a direct response to the question of how do we replace this clearly defective unit?