Intercape Cancellation Stink Bomb

My wife booked tickets for her and our 6 year old to travel to Knysna on 28 September 2015. Our daughter became ill and we tried to cancel but o no avail. So we changed the date (R183.00 added to the ticket price) to a later date (19 October 2015) but now my wife no longer wants to go as our sone is starting his final exams. Intercape says we cannot cancel but needs to change it to a later date (again another 15% will be added to the ticket price). We will be going on holiday in the second week of December and will be using our car, but now i have to flush all that money down the drain because Intercape refusess to cancel. *** policies if you ask me!