Engine cutting out whilst driving

Wonder if anyone can advise. We have recently purchased a second hand VW Sharan, its the diesel auto, and we have a very odd problem.

It started off on a couple of long road trips. After driving for a couple of hours, we stopped at the services, and, about 2-3 minutes after pulling back onto the motorway, the car suddenly lost drive. The engine was still revving, but just no drive. Onto the hard shoulder, put the car into park, back into drive, drove off, no further issues. Same thing happened on the way back from holiday, within 5 minutes of pulling back onto the motorway afte a stop, loss of power, popped into park, back into drive and all sorted. No engine warning lights, nothing.

So, things have developed further. Another longer road trip, another stop at the services, and this time, rather than losing drive, the car stalled....80mph on a French motorway and total loss of engine and ignition light back on. Pulled over, re-started the engine, drove on fine.

It seems to be getting worse, bearing in mind this is an automatic, it stalled 6 times as the wife tried to reverse onto the driveway, much to the amusement of the kids, and it seems to be revving very high before changing gears. I've brought a diagnostics unit and the only 2 error codes we're getting are

19463 and 16706

The car is really tidy and we've got it serviced and updated. It did have an issue with one of the gearbox seals, which we've had fixed, we just need to try and get the stalling to stop as its actually pretty dangerous and we've been fortunate that its only happened on roads wide enough to be able to stop on.

Any pointers on either of the above error codes, and, perhaps more importantly, whether they're likely to cost a fortune to fix, or if this is something I might be able to attempt myself?

Many thanks for any info anyone might be able to share.

Cheers