ahazoor - I think you should fire your mechanic and find someone else who knows how to repair cars - not just disassemble and reassemble and pray for it to work.
You have had sooo many questions about the engine part - that it seems that either you car is a complete dead case or your mechanic has no clue about his trade.
Check the system for intergrity - search my posts - ive posted on how to check for leaks with a pressure tester. Once you found the leak sort it out, do not omit the obvious of radiator cap flange leakage or even a small puncture in the overflow pipe (high possibility as the stupid radiator repair shops and mechanics usually tear it)