I'm unable to install a security app

IT won't let me do this. I have a iPhone 6 with 16 gig and some one will not let me install a security app but they copy everything and like a dummy I took password or left off after wiping out all my contact and reinstalling! Not really sure who but no land line and unable to call payments in without them getting info or get on Internet to pay bills, and they installed a payee on my bank account! I had to electronicly send entire soc sec check to mortgage co. And now wondering if they are for real after seeing my house on web for sale and I was no longer the owner!! What do I do?