Shropshirelass, I usually react the same as you to these things, but there are some slightly different factors in this case that have come to light. Firstly, photographic evidence in a photo that has not shown signs of faking to any expert so far, shows that Andrew was in fact in the same location as this person when she was a young girl. Innocent enough looking photo, true, and he might not be able to remember everyone he's ever met. Secondly, photographs show that Andrew's memory has let him down over a) whether he could sweat around that time in his life, b) whether he showed affection in public (he's shown in intimate clinches with women at parties, and c) whether he was a party goer and d) that they had a rule that either he or Sarah was always with the girls at any time - in fact when the girls were 10 and 12 both parents were away from home at one time. None of these things is bad in itself but it does show that there were many inaccuracies in his account given to Maitlis.
Wrt Giuffre herself, from what I have read it seems she was approached for evidence, as a person identified as being connected with Epstein, rather than putting herself forward. The part of her evidence that was struck out was not due to being false but because naming Prince Andrew as a party was seen as not directly relevant to the case against Epstein.