“During our purchase of a home, we asked the buyers to pay to have a radon system installed. They agreed and had somebody come out and give an estimate. The sellers signed the contract and then subtracted the estimate from their earnings and put it aside for us to use when we decided to have it installed. We had them come out to install it, and were sort of surprised when they had no idea where to install the radon system. After running around our house for an hour, they gave us a choice, we could run it on the outside of the house, or we could run it through the inside of the house, hidden from view. Obviously, we chose to have it hidden from view. Then finished their work and left. The next day, the owners called and said that we owe them 500 bucks because THEIR installers did not follow what was written for them to do on the contract. Our name is nowhere on the contract- the previous owners are the ones who agreed to whatever was on the contract, all we cared about was having them come out and put it in. They said WE are responsible for not making sure that the installers were following what was contracted. Who is at fault here? Them or us?”
To answer this, you need to look at the contract–not between the sellers and the installer, but between the sellers and you. What exactly was agreed between you, and how did that differ from what happened?