Td5 auto gearbox temp issues lost gears

Hi guys & girls
I need a little advice please
I was towing the caravan back from skegvegas today and we stated to have a few issues
First when climbing a steep hill with foot down i would get lights on dash D & M flashing, to reset i would pullover, choose park turn off car retart and off we go till the next big hill then same again,this happened three times in 90 miles over 2 hour,
But with only about 18 mile left we got a new light a red temp light i belive was auto transmission temp....so we pulled over and had 15 mins to let her cool down drove 5 more mile and it came back on.
So this time i pulled over for 30 mins to cool and we got home just but it didnt feel like the gear changers were right!

So i go to revese van into its home and no reverse! Dam
I get van off and get home drop auto trans oil about 4.5lts & replace with about 5 ltrs and yes it was burnt and black,
I have not done filter as it was 4pm sat and didnt have one
I now have all forward gears but if you boot it even on flat M & D on dash flash
Reverse is there but almost unuseable

Any ideas please
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Youneedanewgearboxpal.com
Cheers steve
mansfield notts

Check the oil level and colour

Oil level was 1/2 ltr down and black as black gets with a hint of red

I suppose it could be possible you had two issues. The D&M and no gears issue could be XYZ switch playing up and the temp could be needed oil change which you've done because it's getting too hot for the old oil you had in while under towing load. Would be a coincidence they happened together obviously...!

Yeah after a bit of reading am thinking clutches have gone
Anyone got a gearbox for sale