Mohtaram Waqas Sahib,
You seem to be facing a problem in the shocks. You have been using 'Kabli' ones which are used and may have been abused in the past. I always use 100% genuine brand-new parts in my cars no matter how expensive they are. You can use any good brand of shocks, preferably Japanese if you can find them, with the specifications of your Mehran's stock shocks (ones which come fitted from the factory). Any good Japanese made shocks matching with the stock ones will do.
I maintain my cars like commercial jetliners in which taking chances with substandard parts have to come down to zilch. Imagine a spare part failing at 40,000 feet in a Boeing 787 if you use substandard parts.
I will narrate a GM's (General Motors Corporation) scenario with its Saturn division. GM's Saturn was a very good brand when it was introduced several years back and the cars were selling very well and GM was making lots of money from this brand. GM wanted to cut cost by switching to part suppliers (vendors) who offered parts at a lesser price and she (GM) did switch to those suppliers by ending contract with existing suppliers who were already supplying the parts at higher cost. But there was a big catch! The quality of the parts supplied by vendors at reduced price was poor and problems started to surface with lots of Saturn cars. Rating of Saturn cars went down and sales plummeted. Stunned by the alarming situation GM again switched to their old suppliers (vendors) who were supplying them quality parts but at a higher price and sales started to bounce back again. GM learnt their lesson the hard way and I don't think your case is any different from their's. :P:P No offence please, just kidding. Just switch your parts to a good brand and you will be all set.
Unfortunately GM has ceased production of their once quality Saturn brand.