Ford galaxy - transmission limited function

[Fishcake1552]

I have a 2010 ford galaxy titanium with automatic gear box.  A couple of times an error message saying 'transmission limited function' has come up on the dash when the car is stationary and the car won't then reverse.  On both occasions it's righted itself when the engine has been turned off and on again.

i was driving to work the other day and the warning sign came on whilst I was driving and the car sounded like it couldn't find a gear.  I had to pull over and turn the engine off and on again, it again righted itself once the engine was turned back on.

it was put onto diagnostics which revealed no error codes and they're suggesting we have the gearbox stripped at a cost of £500 plus.

any ideas what could be wrong?

thank you