SAA :- Terrible service and misleading

I booked a return flight on SAA in January for October to London. I was unsure on the dates as it was so far in advance but was ASSURED by the SAA staff member that if i come at a later stage we can simply change it at NO EXTRA COST. I have since been to SAA offices to change my date only to be told it will cost $136.00 for the change as this is a minimal cost to change a ticket and if i want a flight within 2 days of my option need to pay $800.00 extra. However online economy tickets are available for dates i requested so i questioned this only to be told that there are actually sub classes within economy and SURPRISE my ticket was below what is available.<br> My question then is when i booked why was i not offered these SUB CLASSES as these are not even an option on line and i if it increased my chances of securing a seat i would have more than likely opted for this.<br> <br> I have been twice to speak to the manager who is not willing to meet with me and always \in a meeting"but available until the reason for my visit is identified.<br> <br> On talking to people this is apparently a regular occurrence"