National Power Supply Larry Pryor Wrong Engine Sent and National Power supply refuse to pay to have engine modified Yakima, Washington

We ordered a engine from National Power Supply for our tour coach. We were told  the engine would be delivered within 2 weeks. 4 weeks later we a engine was delivered, damaged. Upon further inspection is was discovered to be the WRONG engine. National Power Supply istructed us to contact the builder (whom they had a contract with) the  build stated that they were provided the wrong ID number and that we indeed were sent the wrong engine. The builder agreed to send the parts (free of charge) so that we can modify the engine for our use. Since It was National Power Supply Supply provide the builder the wrong number I request that National Power Supply Pay  the labor cost of $2979 that is required to rebuild the engine that was sent