Inferior repairs and insufficient warranty

My iphone is insured through Vodacom. In December I had the screen replaced, paid the excess, and was told there was a 6 month warranty on the new screen. Now 3 months later the screen is faulty, it has stripes all the way down it and I am unable to use it. According to Vodacom, the warranty only applies for 3 months, and even though we are only about a week over the warranty period, they are unwilling to do anything for me. The screen they used for the repairs is just a generic screen, not a proper iphone screen. I could have gone to a backstreet repairer, had the same inferior quality job done, for the same price - what then is the benefit of paying for Vodacom insurance?