failed to proper service the car/broke engine

I took my car for service to Volkswagen NTT in Heidelberg, after receiving my car it had problem I phoned them to report the matter, but I was not assisted as I was told that their machines that services the car reported that it was ok. Few weeks my car engine was damaged, I again called them and I was told to it was my fault and so I must pay R60 000 to fix it yet im under warrant. I then contacted Volkswagen South Africa, to report bad service from the dealership and a lady by the name Zukiswa told me its my fault that the car was broken without even asking me what happened. Please assist me.