I'm not South African but I spend ten years a year in that glorious country if that counts for anything...
If you're a South African living in the UK, it sounds like you have a good chance of getting your Q5's engine fixed for free. If however you're a South African living in South Africa, you may not be so lucky. If you have already spoken to Audi SA and they have said 'Voetsek!', then you can either shell out for an engine rebuild (costly!), sell the car on to some other sucker (unethical!) or you could try something I have long advocated, which is to try running your car on a less volatile engine oil. The last time I went to a branch of Midas, you could get Shell HX5 20W50. The new stuff (look for A3/B3 on the back of the can) is actually a very good oil. Don't do this if you think there is even the remotest chance Audi SA will fix your engine for free because if you do do it, they will use the non-standard oil as a reason to wriggle out of their obligations. If you want more explanation on the reasons for using a heavy, less volatile oil, read some of my previous posts. Good luck!