No interest in resolving a complaint

I bought a VW Polo TSI from the Silverlakes Branch some 40+ days ago (End November 2023). I bought the car for business since December is out peak month. Only ONE defect disclosed on the DEKRA report i.e. window switch faulty. Upon driving out after collection, car lost power and wouldn't drive higher than 10km/hr. Sales person notified immediately. No response. Head office called to help with a resolution process. It was noted that it takes 48hrs to resolve the matter. It's now 40 days. Countless calls to the call center yielding no results. The 12 times I've been told I'll be called back, only once did it happen. I've had to take this car to numerous workshops at your instruction ti get quotes to FIX. These have been shared and no help still. Today alone I've been on a call 5 times. No help. I have in the process lost over 20k of guaranteed December revenue. I've incurred interest on the "loan" taken to purchase the car. I do not have a car. What should one do to get help? ***