Kitten Won't Leave Older Cat Alone?

I have a female cat (Jess) who's just over a year old, she was with another cat, but she and her owner moved out a few months ago. They got along well, eventually.

I bought a new male kitten (Tigger) to keep her company and they aren't getting on. She hissed and growled to begin with, and he didn't like her, but they are over that now.

They can be in the same room together and they are mostly fine, but he keeps aggressively playing with her by jumping on her back and biting her face and ears. She cries out sometimes and she always pins him and tells him off for hurting her, but he's always straight back on her doing it again. He will chase her around the house and give her no peace until I have to separate them (even as far as he won't let her go to the toilet). I don't know what to do with them anymore, short from getting rid of Tigger and would like some advice.

By George