Have you joined the facebook group?
https://www.facebook.com/groups/955027937948541/
The best course of action will depend on how long ago it was "fixed" (Broken!)
Earlier versions can be rolled back by a good re-mapper - you will have to pay, but its the only way. Dealerships will refuse to.
Newer versions of the update (in the last 5 weeks or so) are very difficult to rollback and will probably require removal and flashing of the entire ECU. It appears VW have built some sort of failsafe in now to stop tuners making money out of their screw-up.
Personally, i'd cancel your diagnostics visit with VW. They are going to tell you everything is fine. They will probably also charge you for the diagnostics. They'll also update it to the latest version, which will be just as bad, but harder to reverse. Read some of the horror stories on the group above. (There are over 6500 members now).
Sorry to be the bearer of bad news!
You can join one of the legal campaigns, but i'm not sure how fruitful that will be.
I'd get shut of the car if you can take the hit - I can't afford to! Mines not fixed, but I paid a premium price for a mint, low mileage Octavia VRS, literally weeks before the scandal broke. Prices have now fallen through the floor so I've got to keep it. I love it, but I don't want the performance or safety compromised by having the fix. I don't see why I should lose out because of a multinational scandal?
I've also prepared some answers before someone pipes up with the following:
"Not all vehicles will develop issues" - I know this, but why would I take the risk?
"I had the fix and my car is fine" - Good for you, but for how long? And why should you have had to have it anyway? It's about the whole principle.
"I'm a mechanic for VW and this is all BS......" - Seriously - don't even bother. I've read enough horror stories to convince me. i wouldn't waste your time.
Good luck!
By offering a guarantee to replace parts which fail after having the fix done for free, up to 2 years after the fix tells me they know the update can damage vehicles.