Ridiculous fees for changing ticket dates

I needed to make a change to 2 flights booked under the same booking using Travelstart. As the tickets bought were not flexible tickets, I was fully aware that penalty fees would be required. However, they informed me that the fees charged were the following PER FLIGHT: - Airline fee difference between the flight dates - Airline penalty fee for changing dates - Airline tax difference - Travelstart handline fee (R598)

Whilst the airline fees make total sense, Travelstart charged me R598 PER FLIGHT to make the change. Had I booked the flight directly with the airline, I would have saved myself R598 x 2. They could not explain to me why the fee is so high and why it is charged per flight. The monthly fees for my bank account are far less for much more value. As an intermediary, there is no reason why their fee must be so high, nor charge it per flight. I will not be using Travelstart again as they do not offer a valuable service for the costs that they charge. In addition, there was no attempt to try to understand my point of view, other than throwing very vague terms and conditions at me which actually do not stipulate this charge per flight explicitly. Had I known they would be such a rip-off, I would not have bought my tickets with them.