The car's Automotion plan should cover the cost of the gearbox being fixed/replaced as the car is still under the 60,000km limit. If they don't want to replace it because it is expiring soon then give them hell (or extend it for another 30,000kms - it costs R12k to do so).
Just make sure the mileage doesn't go over 60,000kms!
+1. I had to replace the gearbox on my car about 4 years ago and it cost R35k for a new gearbox.