What's best to do?

[Norrs2]

OK, My A8 3.0tdi gearbox has gone. It still moves but won't change up from 3rd and there's some mechanical grinding noises.

It's done just over 200k. There's relatively new 19" wheels & tires and it had a new Turbo at 120k. Has a remap also.

I feel it's too good to scrap but I've replaced the car now and haven't got the gumption to try and fix it. £1800 to refurb the box.

Any suggestions???

TIA