Window opens whilst driving & when turn the engine off?

Hi, i have an 03 Renault Megane Hatchback & am regretting purchasing this deeply.

I've had many a fault with the car so far & have only owned it since August.
Anyway my most common problem i'm currently having is when i turn the engine off, take the key card out, open my door, the rear window behind the driver opens fully...for me to then have to place the key card back in, start the engine & hold the rear passenger window control on my panel up so as not to open again.
Not only is it doing that, i've found the window to have come down fully whilst i'm driving aswell, happening a lot more frequently than when it first started happening.

Anyone else having/had this type of problem & if so, any advice on how i can get this fixed without me having to be robbed blind???