Incorrect cancellation

I booked a flight for my mother and I. Before my ticket was confirmed I notified the agent that I no longer required the ticket. After much back and forth, the ticket was cancelled and I received my refund. <br> <br> Today I checked in online and found that Travelstart has erroneously cancelled MY ticket, rather than my MOTHER'S ticket. <br> <br> I am now told that the best they can do for me is cancel my mother's ticket and I should pay for a new ticket, which is about R2200 more expensive. <br> <br> This is completely unacceptable and I am disatisfied with the general service received.