SOLVED. Recent early YA British contemporary fantasy series; shadow children, nasty vines. [s]

[Teresa]

This series came out within the last 10 years. It's on the young side of YA--is there a name for that? The main character is a girl, but there is also a boy involved in most of the adventures. It's British.
Things that happen in the series but not necessarily all in the same book: They use the very hot hood of a car to do something--read a hidden message? There's a block of flats with the ghosts/shadows of children that try to pull her in. In one there's a creepy chemist's shop, a parallel world where they meet a girl with stripy socks sitting in a tree, carnivorous vines that chase them down a path, and (I think) a sneaky trap with bottles or mirrors. They break into a theater. The boy's parents own an electronics shop. She likes parma violets.
I *think* she can see ghosts and lives with the ghosts of her mother and father, but that might be mashing a different book in.
I read these less than 5 years ago! I don't know why I can't remember the name.

[Ayshe]

Spellbinder by Helen Stringer?

[Teresa]

That is either the one, or one that I mentally mashed up with some other book. Guess I'll have to read it again and find out!

[Teresa]

Spellbinder is it! Thank you Ayshe! Everything I remembered is in there, even the stuff I thought I might have mashed in from elsewhere. Except for the stripy socks, which I seem to have invented whole-cloth.