Delayed SAA flight

I'm at East London Airport and the SAA flight that was supposed to depart to Durban at 7h35 will depart at 9h00 when I'm supposed to connect a British Airways JHB flight from Durban at 9h00. SAA refuses to assist in arranging a later flight at Durban to JHB because it's not their connecting airline. British Airways call centre wants me to speak to the agent when I've made a booking personally and paid with a credit card....what a bad service from the airlines. Don't know what I am going to do when I get to Durban.