Very Poor $ Unprofessional Service

I am complaining about the poor service rendered by Spargs Build IT ***) in a small town called Libode, Eastern Cape. We bought Roof sheets (IBR) on the 9th of September and were promised delivery within 5 days however, this did not happen. It has been over 9 days waiting for this material. It is unfortunately affecting the integrity of the timber used for roofing as it was already installed awaiting the roof sheets. We've requested for a refund so that we can go elsewhere but they are refusing to give us a refund. This is absolutely poor service and we should not be held at ransomed due to their oversight. When I contact regional office KZN (***) nobody picks up the phone. Can someone assist me in at least getting my refund so that we can go elsewhere before the timber used is destroyed.