Warranty query

I bought a new charger (adapter) in the month of July, I payed a sum of money for the product however the other day plugging it into my usual outlet it went up in sparks and “exploded”. I went to the Istore to replace it, since it has a 1 year warranty on it. On the box it specifies that it is high voltage protection. Luckily I was at home since it could have ended worse. Explaining my query to the istore team they simply said it is not faulty from their side they cannot replace it for me and also I quote “the voltage of my place was maybe high that day” I really thought they would help but only help if the charger just stopped working, this was a fault from the product it self