Terrible customer service and theft

I booked a ticket on Friday evening with my ebucks. When confirmation came through I was not on my selected departure flight but a much later time as my girlfriend. We were sitting next to each other booking from separate devices as we were using our ebucks. I immediately sent an email. But it was late Friday evening. When I called this morning (Monday) I was told I would have to pay additional R1180 for flight to be changed. After I complained about it they waivered the changing fee of R342. I still had to pay a difference of R873. This is ridiculous and is theft. Mr Lee Zayeed basically accused me of lieing stating \well why didn't I report it straight away"well Mr Lee Zayeed. I did email it in straight away! Pathetic service and theft. """