There is only a one solution to this problem i.e. Hair transplant. Because no medicines or oil can give you positive results.
If you were unable to get a referral, try looking yourself for a good hair transplant clinic in your local area. Don't depend on advertisements, sponsored before and after photographs to make your decision.
Now some clinics like Dr.Cole Hair Transplant group are providing free online consultation services with professional doctors that can help you make an informed decision.