broken engine mounting

My husband purchased my vehicle in August 2013 with and extended warranty from Durban South Toyota( DST-Amanzimtoti). In January 2014 the engine mounting broke as well as the ignition mechanism. we were informed that the engine mounting had been repaired just before we took ownership of the vehicle in August 2013. Bosch repaired the vehicle at the Dealerships cost. Within 6 months the exact same part broke. My husband went direct to Bosch this time and they repaired it. . almost 6 months later again, the same problem occurred. My husband took the vehicle to the mechanic and was informed that the same side engine mounting was broken again. He then took the vehicle back to Bosch in February 2015, this being the 4th time. they informed us that Toyota instructed them to fit inferior parts.Toyota has denied this. Bosch fixed it only in May 2015 claiming they had to wait for the original part and they had to use my warranty.but on inspection we found that inferior parts had again been fitted.about 2 weeks ago the same part has broken again.Please can you assist in this regard.