Where is the main circuit board located on a 2005 renault meagne 3door? ?

Hi, could somebody please tell me where the main PCB is located on a renault megane 16v (2005)?
My electronics are buggered, but i think the dealer is trying to screw me on the warranty.
He says there's a leak on the back left wheel arch that has fryed the electronics main PCB.
As it's water damage, they say it's not covered by my warranty.
does this sound right?