Return ticket to Johannesburg from Delta Couches

I bought ticket to Johannesburg from Cape Town ,ticket shows bus depart @13:00 from Cape Town Station but till 18h00 I was waiting for bus, I ask service consultant but I couldn't get answers and they told me there is no refund instead I must take voucher what must I do with voucher ,I had to book flight while waiting for their answers because I had to be in Johannesburg @7next morning , I am very angyr and I need my money back