Volkswagen Polo 2015: Problems with GTI DSG

I bought a 2015 Volkswagen Polo GTI 1.8T DSG in May. The transmission developed a fault in mid-June with only 1500km — when changing between second and third gears in Tiptronic mode, there was a "clunk" and the car jerked. The initial advice was to have the transmission replaced, after a 12-day wait for it to be shipped from Germany. Then VW Germany said a replacement transmission would not fix the problem and a software update was required. After four weeks' waiting for the update from VW Australia, I was told the software update was available but might not solve the problem — and advised not to drive in Tiptronic mode. I'm concerned there is no urgency to fix the fault.