Continental Tyres - Bad batch

I have never had this bad service on Tyres in my life. And i have been driving motor vehicles for more than 35 years. My first new bakkie I buy, I get a bad batch of Tyres. Continental Tyres SA is not answering my phone calls. The head office numbers always busy. Between 08h00 and 17h00 tells you the line is busy. I send a complain on the website no response. What a pathetic group Continental Tyres SA. 3 Tyres cracked in the first 40 000km and noooo it is not potholes as they claimed with the first tyre.