Auto Tire Unscrupulous Mechanics tried to pull a fast one in regards to Thermostat. St. Louis Missouri

 In February of 2015, I was made aware that my thermostate would need to be replaced because it was leaking and you could smell it. My husband usually does all the work, but didnt have the time. I took it to Auto Tire based on what my husband said was wrong with it and, after the inspection of the car the auto mechanic there came to the same conclusion. I had a new thermostat housing put in with a coolant flush and fill which came to about $345.00. About two weeks ago I notice a smell coming from my car and ask my husband to check it out. He determined that it was the thermostat. On December 10, 2016, I took it in to Auto tire so they could check it out. I know that I had just had a new thermostat housing put in so I figure it had to be under warrant, and informed the mechanic of this. I was then told that what they had fixed was the upper housing which is under warranty, and now the lower housing would need to be replaced. On the receipt of the work I had done, it does say that only the upper housing was replaced. It says that I had a thermostat housing put in with a coolant flush and fill. My husband, who is in the mechanic field himself says that nobody puts in thermostats in parts. I feel that they did not want to honor the fact that the thermostat was under warranty, by telling me I needed the lower housing replaced so that they could get paid for doing it. I think that they are a bunch of unsavory characters and would like for them to be held accountable for their actions.