Sprite size collision not working properly - overlapp

Hey lads!!
So i have two sprites, a ground and a balloon.
The balloon has physics on and a touch event, and a size increase and decrease, which uses scale to increase.
The collision tough isnt good, i try to increase the size before i shoot and it overlaps the other sprites, which looks like the sprites collision is not increased but the image of it.
Theres a simple work around this by just changing the sprite instead with correct collision, but that makes 3 levels of balloons and alot of future development harder.
Is there a way to increase size of the collision aswell?

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