Help needed. I'm trying to find the name of this film

[Seppo]

I saw a horror movie that freaked me out as kid at least more than ten years ago. I have tried to remember the name or find some clues as to what film it was.

Now the movie. It's about three kids and their mother, who go to their grandmother's mansion for a reason I don't remember. The granny turns out to be a child hating psycho, and she locks the children to the attic. They live like many years locked up in the attic. Their mom doesn't help them.

I don't remember much details, but I do remeber the granny lifting one of the kids in the air by pulling the sucker from hair or ears. I also think the kids had their vengeance at the end by poisoning their mom or the granny, but I'm not sure. I'm pretty sure the movie is from the 70's or 60's.

I really have no clue so any hints you might have are great

 

[Seppo]

Surely someone can give me a clue? I see a lot of movie lovers around here