how do i fix this

About a year ago, my brakes were making noise as if they were needing replacement. I traveled out of state and had the brakes repaired - replacing rotors and pads (??) on all four wheels - in September. At the time, there was still noise, which was assumed to be the dust that would work itself out, however, they have continued to make noise since that time. Recently the noise has become much louder and much more of a grinding sound. When the tires were replaced recently, I did take a peek at the rotors and don't see much wear or signs of scratching as if something were stuck between it and the brake. The brakes seem to be operating fine (which they actually seemed to be when I had them fixed last September but didn't want to take chances). A couple times I have wondered if there is something that is not properly fully disengaging on the brake - the noise sounds quite a bit like the noise made when the emergency brake is not disengaged and someone attempts to drive. Any suggestions? Thanks so much!