Conure Screaming Problem

Hi there, first post here on Parrot Forums. I have a beautiful green cheek conure who is around 12 or 13 years of age. Benny was brought into our home when I was very young. Due to personal problems he was given to an uncles girlfriend at the age of 2 or 3. We did not know that he was not being looked after properly. The person who had Benny did not take him/her out of the cage for months at a time. When I heard this I was absolutely disgusted. After telling my parents this we all decided to welcome Benny back into our new home for good. I go to school and mom works all day, leaving just my dad home (who works from home). Ben is very scared of my dad due to his deep voice (I'm guessing). Ben seems to have chosen me as his mate and he likes my mom, just not as much as me. Anyways, long story short Benny screams all day long when my mother and I are not home. He's driving my dad crazy lately. If you need anymore information please feel free to ask Thanks for your help in advance.

Does Benny have toys to keep him occupied during the day? Anything along the lines of shreddable toys and foraging stuff? I know when my conures have something to destroy they won't make a peep.
Can Benny see your dad when he's home alone? I'm just wondering if it's an alarm call?
Also if your dad is calling back at your bird or giving him attention it could exacerbate the screaming (if it's attention seeking).
Because he's an older bird I'm assuming he's pretty set in his ways, so changing screaming behaviour is going to take a lot of time. Best of luck!! There'll definitely be people along with more advice, in the meantime it might be worth searching through the forum homepage for screaming, it comes up a lot! =)