Renault Northcliff Bad Service

I booked my Renault Clio 4 (DT 56 JX GP) into Renault Northcliff on 23 October 2019 to get a water pipe replaced under warranty. We are now sitting on the 20 November 2019 and still they (Renault Northcliff) are still waiting for the part and they can't provide me with an explanation as to the delay. When we booked the car in they said it would take a maximum of 21 business days to be sorted out. I called on 19 November 2019 in the afternoon to arrange a loan car and was advised they there are none available. When I did a follow up on 20 November 2019, I was advised that I needed to be in contact with the Customer Service Department in order to arrange a rental, after a call with them they advised that it is the responsibility of Renault to send the forms through. I would REALLY like this be sorted out ASAP as this is not the type of service that I expected to receive from Renault and it now makes me doubt the Customer Service towards their Clients.