Help! car escape artist

Ella has now figured out how to undo her carseat and can get herself out of the carseat very, very fast now. We got one of those houdouri (sp?) clips things a while back, but she figured out pretty quickly how to undo that as well.

I have been talking to her about the importance of carseat safety etc and using Dora as an example "Dora says seatbeat on so we can be safe", but she just gets this really cheeky look on her face and does it anyway.

SO, can anyone recommend any products on the market to get combat this problem. I have just been into babycity and was looking at a product called the Angelguard, so was wondering if anyone had used that and if it actually worked?

*sign* NOT  a good time to learn this new trick.

thanks for those suggestions.

Ange221- yeah it's the booster seat seatbelt she keeps undoing.

As soon as she starts to get out I pull over staight away.

i saw the blue clingy thing, but after having a play with it decided that she could probably undo that as well.

Her fav daycare teacher had a talk to her about the policeman telling her and Mummy off, if she got out of her car seat and then we had a big talk about it.