For them to do your 18-20weeks scan ?

I had mine done last week and i feel as if they where very quick with it. The scan lasted 10mins but when i have had that scan with my other pregnancies i have always been in at least 20-30mins. I'm sure they are meant to check the kidneys and everything but nothing was said. I'm a little worrried as Alex was born with kidney problems but with him nothing was picked up till 36wks as they missed it at the other scans. I just want to make sure everything is okay with this baby.
I have to go back at 24wks to have the heart looked at again as they said they couldn't see it very well but it did look ok.

Will i be able to book to see someone else for that scan or will i have to go back to the same place ?