VW Fuel - Spark Plugs Issue

I bought my car new and I took my car in when it gave me issues - mind you this car is still under Warranty, Motorplan & Service Plan. Then I was told my plugs are damaged due to bad fuel and now I have to pay using my money and non of the plans will cover that.

Why was I not informed that some garages have bad fuel? Why are they not covering under all these Warranty, Motorplan & Service Plan? What was the point of buying this new car?