The yard may not have to pay for his labor costs if the warranty in question only covered parts and not labor. When you purchase items from a salvage yard, the fact you received a 6 month warranty is great but it is in many ways assumption of the risk for lack of a better phrase. If your warranty is limited and you contractually agreed to a limited warranty, you may not require them to pay your labor costs. Think about filing a complaint with the entity who oversees this company's licensure and may be through that complaint you can get some of your labor costs back.