Brakes make a clicking sound when I come to a stop (break)

I have a 2003 ford focus with 45,000 miles about 3 weeks ago I had the rear breaks changed @ pepboys because I was having a screaching sound when I breaked. When I took the car home that day I notice I now had a different sound when I breaked it was grinding so I thought it was just the new breaks and it would go away. Well not only did it on go away but a couple of days later I started getting a clicking sound when I break so I took it back to pepboys and left if for the day well in the afternoon they called and said ok we worked on it now everything it working good so I drove it home and had the same problem but now 2 times worse so I took it back the same day. I did a test drive the the service tech and he stated wow it was not doing this when I did the test drive. I was like what! that the reason I brought it back in the 1st place. So he said to leave it overnight and they would work on it. I had the car pickedup the next day after pepboys stated everthing was fine. Everthing seemed fine until about a mile later when I heard the grinding and the clicking all over again so my question is. What can the problem be if I just had the breaks changed and now it's clicking and grinding?? Please help me I need to know if they ruined my rotors, drums, or breaks??