L322 gearbox problem 2010 TDV8 Vogue

The ongoing saga of this car, since I bought it in mid September there's been an occasion; clonk when changing up/down at about 50mph. Today going up Detling Hill in busy traffic going up at about 50, it kicked down,clonk, changed op again, revs increased, then changed down again. It done this a couple of times then at the top of the hill was doing abut 3000 rpm at 50mph gearbox failure warning came on. It's a very busy rod and the car was still going to I carried on to my destinatiom at Sittingbourne. It seemed to be stuck in 3 or 4 as it would ull away from trffic lights and do 50 in the same gear. At my destination, I switched it off and on a couple of times, tried reverse ok, forward ok, manual mode 1,2,3 ok. Drove it back home no problems! Any ideas? Low oil? Sticky valves? No warning light on now.

6 speed?
Which TDV8?

J

6 speed, 3600cc I think...the facelift version.

A visit to terrain at Bexhill proved enlightening shall we say. the Autologic Quick Test Repot came up with 3 pages of defects, the most significant was in the transmission control model:
U0128-87 lost communication with parking brake control module ( a recurring theme)
P0730-00-Incorrect gear ratio
P0735-00-Gear 5 incorrect ratio.
In simple English, it's f****ed!
It seems the missing parking brake control module is causing a lot of seemingly unrelated problems too, 9 items in all.
Methinks a strongly worded email to the dealer is in order.

I wonder what the jury will make of this lot! Autologic report.