Just a thought:- the handbrake cable will only need adjusting if it has stretched - on modern cars, the handbrake action is very light and the cable is a pre-stretched twisted Bowden cable, so unless someone has been a gorilla with it, I'd doubt if that is the
problem!
I've forgotten, so has your car got rear drum brakes or rear disc brakes?
If it is rear drum brakes, then I'd expect that the auto adjuster wedge is not doing its job and the rear brakes need sorting out!
I'd never ever tighten up a cable to bring the handbrake travel down to 2 or 3 notches, unless that equates to a handbrake handle "angle when on" of 30 degrees - I'm adding that "get out" as some cars need the handbrake handle lifted quite a bit to reach the first notch. If you overtighten the cable, on certain suspension positions, the brakes will get applied a bit - even although it is a Bowden cable.
BTW, my daughter's late 2009
Ibiza 1.4 SC has a handbrake that in my eyes is higher than it could be, and I know that the auto adjuster wedges seem to be seized, a job for the summer I'd think!