Do respect the above comments from the members.. consult with all the garages mentioned above and check with a approximate quot. If its going more than 1k above... then,

Visit street no 24/23 (scrap yard) for a new gearbox from the accident cars. It will be incredible superb because of the accident cars may be new ones'. And it may cost you less or equal 500-800 Qrs (note:engine costs from 1000 to 1500).

They will give you guarantee for the gearbox for 7days as well. If it sucks, return back.

Note:May be you have to return the old gear box with the purchase. Best of luck.