Horrific of them, I'd say request they do an amniocentesis it sounds scarier than it is but gives you completely accurate results if those abnormalities are a big issue for you x
They couldn’t get the measurements at my 12 weeks can because baby was mis behaving and wouldn’t go to the position they needed so said I had to come back at 16 weeks. I asked if I could come back a few days later instead as I know that means they can only test for downs not do the full screening and they said no only 16 weeks no. I appreciate your frustration. They did say to me there are usually visible issue with the other tests and everything looked normal but that didn’t really reassure me as I didn’t think it was exactly putting me out giving me another appointment when my scan was at 12 weeks so had another 2 week window before the 14 week cutoff
You can get the tests for the others at 20 week scan I was told. I managed to get measurements on my second attempt at 13+6 so I was lucky as just before cut off.