Sleepmasters refuses to accept responsibility of defective product

I bought a bed from Sleepmasters in Woodmead. A few days after accepting the delivery of the bed I started to unwrap it and found a big hole on the side of the base. I reported this to the store and they said it must have been damaged by the Warehouse personnel. A few days later they responded and said that the Warehouse personnel did do a quality check and it passed. Now the store, warehouse, and delivery personnel are not accepting responsibility and are refusing to exchange or refund me.