PC warranty problems can’t have replacements

We, the end -user have always been the loser when it comes to warranty on our personal computers. It has been an experienced in our office that computers back down not longer than a year or eleven months or so. The said unit was returned back to the supplier for the one year warranty on parts and labor. Only repair has been done without replacement of the defective hardware. A month or less the problem occurred again but we cannot bring back the unit to the said supplier for it's already out of warranty. How can we have a replacement of the unit rather than a repair on its part, the first time that we brought the unit to the supplier?
