Brand new Sportage with faulty satnav

I purchased a brand new Sportage from the Weltevreden Park branch. Car is great and I'm enjoying it. However, the Satnav system that was fitted to the vehicle stopped working after 4 days of taking delivery. I took delivery of the vehicle on the 27th July 2015. The company that supplies the Satnav system brought me a card with different Satnav software but this does not work properly. I have since made 2 trips and the Satnav would've been very useful. I have asked the Weltrevreden Park branch to escalate and resolve with their supplier but a full month later, I still don't have proper answers. Please could you escalate this and come up with a solution as I am now fed up of contacting the branch and waiting.