Bad service and unfair treatment

We bought precast slabs for fencing from the Amalgamated Precast CC, Wilsonia, East London. Their prices are inclussive of delivery and as such we considered buying from them as other service providers were not delivering the material sold. On the 17 September 2018 they delivered some of the material purchased and we returned 15 cracked slabs out of 100 delivered. When we made a follow up on the next or remaing batch of slabs they said they no longer deliver or we must pay for delivery. Their email: **********