I have had my car at this location 3 times within ...

I have had my car at this location 3 times within the past week. The first time I had the thermostat and housing replaced because it was leaking. The next time I brought it in because the check engine light came on and the code was reading thermostat, which they in turn replaced because it was stuck open. Tonight I had to once again drop my car off because this time it overheated. This is the third thermostat that has been put on my car by this location within the past week. At this point I am highly irritated and mad. I beyond being upset. I am a single mother and depend on my car to go to work. I do not understand how someone who has a diploma/degree in auto mechanics can make the same mistake 3 times.