I scheduled a service call to replace a whole house air purification system filter in the attic. When I called for service , I gave the representative the model number of the filter. When service arrived they had the wrong filter and admitted the person in the office made a mistake and no replacement could be made. The tech proceeded to charge me $79.00 for a service call which I have since disputed with my credit card company because the service call was generated to replace the filter and they had the wrong filter. To make matters worse he tried to sell me a new thermostat claiming it was needed to make my purification system work properly. After doing my very complete homework I was told this was not true. My message is to always get a second or third opinion if you do not want to waste your money on things you do not need.