i had my discs and disc pads replaced twice now due to shudder and the mechanics say it is my driving style that does that to the discs. can that be so?

check to see if front bearing is good, also have front end checked out. Tires balanced, alignment ok, etc.

Is the shudder happening when applying brakes ? If not it might be an idea to try having the front wheels balanced on the car. If you are in the Pretoria area , this can be done by Hi-Que in Pretoria North