Very disappointed with VW quality

I purchased a 2014 Golf Gti 7 with 72000 km with full service history at agents . I am 56 years old . I already had to replace the complete thermostat and water pump R 12000 + had to replace a sensor R4000 . My car started to misfire , i took it in for a fault analyses only to hear my nr 4 piston was broken . My car has now got 93000 km . VW please advise how this is possible . This was my dream car , but i am very disappointed.