Originally Posted by woansleftpeg
They can if they haven't installed them correctly, they weren't required to take on the job and doing so suggests that they were confident in their ability to do it right.
Their response can be to say the parts may have been defective.
Would you like to pay us same labor charge as you paid for the install? We can remove them so you can send them back. Then you can pay us again to install them...
When getting expensive parts that require expertise to install, I will ALWAYS let the shop order the parts and I will gladly pay the extra money so the shop will make some profit. That way if something goes wrong, you got the parts from them, they installed them. Otherwise you can have the shop blaming it on the part, the part manufacturer blaming the shop.