Cant change booking online call centre *******

Hi<br> <br> I called in to change my booking as I am getting an error on the website only to be told that you cant change bookings on the website ??? so why give the option and go through all that on the site if you cant do it online. Now the call centre want to charge me almost R700 per person to change the tickets cause im going through the call centre instead of R177.52 per person if I do it online (which apparently cant be done )<br> <br> so now what ????? can you or cant you make changes to your flights online