JazakAllah Anis Sir!
Hmm, well you PMed me as well but I didn't reply earlier cz I have been staring at the roof while in bed thinking about what could possible be wrong with your car.
1) Yaar, you're missing something. Because something happened while they opened the brakes which caused this ghoon ghoon to start. Did they or you, by any means put water on the brakes after a drive?
I have seen mechanics cooling down brakes before touching them cz they're hot enough to burn through ur skin.
2) Another instance that proves the ghoon ghoon is directly related to the pads touching the brake rotors. Vary the force, the sound varies.
3) Yes I reside in Islamabad and yes we can meet inshAllah but after some days because these days I am in my hometown, came here for test preparations and now awaiting admission to a University. I'll be back to Islamabad hopefully in a week or a fortnight.
Btw, I didn't take mine for 1k inspection. Did it myself.
And still thinking over the issue which might be causing this sound. Have you tried showing this to a local ustaad? Make him drive ur vehicle and guess the sound. They usually have very sharp insights.