poor workmanship resulting in loss

I removed my old kitchen cupboard and Bronkies Cut and Edge installed a new cupboard, zink and tap. The silicone was not placed properly, resulting in water damage to my new cupboard. They refuse to assist me telling me to get a plumber, however they did all the work at the time and it was silicone that was not placed correctly. Now I have a rotten cupboard again and they refuse any responsibility.