yazdani paint shop in DHA had such contacts on speed dial, ive seen those guys work, they would take a literal piano wire and use that to cut the glass urethane.
The shop in plaza (amjad glass I think) also had those guys contacts, but only gave them for highly expensive euro cars as the owners would rip the shop to pieces if water leaked in. dealerships also had them.
I'll look in my old notes to see if I can find some leads of them. They were not your usual sheesha walay. They were grads from KU.