Spark Plugs Blows Up After Service in Nissan Kempton Park

I took my car (Nissan NP 2000 with registration DF 85 ML GP) for service in Kempton Park Nissan in May 2019. Yesterday was driving (14 July 2019) one of my spark plugs blew up while I was driving. I started hearing a sound a stopped only to see that one of my spark plugs is out. I tied it up and drove home. This morning it blew up again when I was about to leave for work. I have called IC Auto Nissan in Kempton Park Three Times already and I am not able to access the Service Manager. In the morning they said she will call me at 10 AM today. I have called Nissan twice after my first call and I am unable to reach her.

Regards, Mr Semelane ***