Faulty brake pads

I had taken my car for a service at Renault Newcastle and I was told that my brakes pads and disc plate need to be change. I didn't understand this because I had change my brakes in April of this year with them. Now for me to have to pay for the same product twice in less than 5 month is just outrageous and not fair worse if it was the same company that had changed my brakes. So its either in April they didn't change the brake or the product they use was faulty or not of good quality. And worse they don't t want to acknowledge that it's their fault, they want me to pay for the brakes pads again.