Transmission fault etc

I've seen numerous posts on this fault and a range of suggestions as to cause / remedy. I booked my Freelander 2 into the main dealer when this fault popped up a week ago but, Sod's Law, the error message disappeared after 24 hours not to be seen again. I did take it in and the diagnostics showed this error together with a "Transmission slipping" message. I was told that it was the Haldex pump which, supplied and fitted, would cost £672. I've not had the message since and the car is handling perfectly. So, the question is, do I go ahead with the new pump or do I wait and see? Were the pump to fail whilst on the motorway, for example, and my wife was driving and my three-year-old daughter is a passenger, is there a safety issue? And is any additional damage being cause to parts other than the pump? Any advice, gratefully received. Thanks