Breach of warranty + no reply to all attempts at contact

We had our flat roof in Joburg sealed in 2013 with Sealcraft at a large expense, and were given a six year warrantee on the work. We have since had numerous problems with the roof (including currently in October 2017, where our tenant tells us there is now a torrent of water cascading down the wall). We have contacted Gary via email no less than 6 times about it. We have also called two different numbers numerous times, to no avail (one goes to voicemail, the other cuts off). He has not rep**** to any requests to return to the property and fix the bad workmanship or uphold his contract. Have we been ****med? We know no other way to fix the issue with him and we also have to resolve it as soon as possible (at our own considerable expense), due to tenants living on the property. So if you're thinking of using Sealcraft, AVOID AT ALL COSTS.