Hi to all who have kindly offered advice on this matter. Here is hopefully my final Sit Rep on this topic, which I reckon has been bugging many Treg owners, even if they are not aware how or why their car may have a gearbox 'hunting' issue.
First, ze Bad News:
I asked the dealer service manager to forward me the official response from VW UK Technical on this issue. It reads as follows..."VW Software Update Campaign no. 23DK optimises the interaction between the engine and gearbox, thereby reducing the emissions of your vehicle. Depending on driving style and operating conditions there is therefore a change in biting points in the automatic gearbox, which causes it to change gear at different engine speeds. In certain driving situations the gearbox reacts more sensitively to the operation of the accelerator pedal, so that the vehicle drives in an emission- and consumption-optimised gear. This can cause more frequent gear changes.
It is not possible to reverse the software to the previous version. This suggests the experience you are having is a normal characteristic and cannot be altered either through software or part replacement" . (Anyone else smell the bullshit here....?). The service manager then had the cheek to ask whether I had been made aware that the car's driving characteristics may change after application of the new software; of course I said 'certainly not, but that didn't stop VW doing it, did it?'.
Now for ze Good News:
Having been rebuffed on all sides by VW, I was determined to research other possible avenues to sort the problem. Some internet trawling led me to a company called AVON TUNING (based near a village called Tockington, close to junction 16 of the M5, just north of Bristol); they have an excellent website that describes all their services - www.avontuning.co.uk; this includes gearbox TCU reprogramming. To cut a long story short, having presented my car to them for half a day, their technical wizardry has worked wonders on the car's gearbox, and how it interacts with the engine and throttle; no trace of 'hunting' remains, and the car runs happily in D8 from around 50mph, and stays in that gear during normal acceleration. It has also sharpened-up changes in the lower gears, making the car much more pleasant to drive overall. Avon Tuning do have ODIS and other digital systems that clearly CAN reverse incorrect software. They told me that they found the gearbox change points to be 'all over the place' after a test-drive, and that they found a previous software version (2083) to work better with my original TCU, and overwrite VW's so-called 'upgrade' version (3620, I was told by the dealer). They did advise me that software version numbers are not critical; they can always test to find which software version works best with a particular TCU, whatever its age. Incidentally this cost me £299 including VAT, but was well worth it in my view, as it has totally transformed the way the car drives - so I may keep it a while longer now!
Incidentally, I'm considering how I might report this outcome back to VW, to see if they feel any embarrassment (unlikely), and whether they would consider any kind of recompense, perhaps in the form of some future servicing discount - but no software changes allowed ! (too much wishful thinking, methinks.....).
I hope this encourages other owners to go down the 'specialist' route, and to bypass the dopey dealers whenever possible.
