Originally Posted by corfire
The pros and cons given on here don't really matter much. Bottom line is you are getting bad press. I think you should refund the guy all his costs, and give him a new correct part at a big discount, if he actually wants one anymore (free would be better). Also, let him know that you are sorry for all of the inconvenience the mistake you made created. It's call customer service with a smile! 
This is a lot of bad publicity over one stupid $70 thermostat.
Even if there wasn't a thread going, it's a bad move. Losing a customer over one part isn't worth whatever cost was on that thermostat. What is TVT trying to save? $40? $60? Is that really worth pissing off a customer?