Terrible service! Without a car for 4 weeks now and counting.

Took my Audi Q7 in at Audi Somerset West for a free campaign software update. After they struggled for 4 days for the update to complete my car now has a DPF warning sign which it didn't have before and my car won't start. Quote is R70 000 re repair and I don't have that money to repair. How am I suppose to get my car back? Audi never informed that should the update complete and a fault is find with the hardware that the car won't run or that the amount to fix it would be R70 000. Just terrible service from a luxury car brand.