Mccarthy Vw Durban shifting blame and costs to customer

I bought a new polo tsi life around March 2024. The sale went well. I had a problem with engine management light flashing after about a month of owning. I informed the salesperson who said he will tell vw to record it on system incase it happens again. Four months into ownership it happened again and the epc light came on. The car lost power. It was towed into dealership. The service advisor Estelles immediately informed me that if there is an outside source as the cause they will charge me a diagnostic fee. It was as if they had experienced this problem and knew the issue and that they will shift costs to the customer without a second thought. I was naturally upset as the car is still under warranty. They called me to tell me that the fuel quality is poor and that the plugs a are fowled and I need to pay R 3000 to replace. They also included a letter from vwsa to the dealer saying they are aware of the problem with plugs on many of the vws and that they are requesting samples from dealers. They also indicated that they are approached the fuel companies in the country and are still investigating as it seems it is fuel contaminants in local fuel causing the plugs issue. My question to vw is why it's only affecting vw and not other brands. To me it's clear the vw product can't handle the south African fuel so its a product issue and not a fuel issue. Now they shifting costs to customers due to their inferior product. The is my second new vw in two years bought from the same dealer. The previous was a new tcross from same dealer with the exact same issue which I traded in after a year. When I had the same plugs issue, they replaced under warranty, therefore an admission that's it's their fault. I only fill sasol fuel and not any unknown fuel from any white site. For me they are not consistent just trying to shift blame for their mess and faulty product. Pathetic service. If there is anyone else out there with the same issue, let's expose the inferior product so everyone is aware.