The DPF is basically a catalytic converter for a diesel engine. I wouldn't say it's necessary that both of these things fail at the same time, but it's possible. I will assume you do lots of short trips rather than regular long trips?
At any rate, the DPF needs to periodically heat up and stay hot for a long period to burn off excess deposits. A nice long road trip would be a good way to do this.
Being a fellow South African, the first thing I would suggest is taking the car to an RMI-approved workshop that is NOT a VW dealership. (Most) Agents have a reputation for overcharging and even recommending repairs that are unnecessary. (compare a R45 000 repair quote vs R17 000 from an independent using the same OEM replacement parts). Have your car inspected by a third party and see what they say. On that note, a DPF really shouldn't fail after only 3 years. You see this more often in cars that are older than 7 years or so. The car should still be under warranty, so explore that possibility before you sell a kidney.
I wouldn't expect the replacement of a turbo + DPF to cost more than R20 000 max.