What to do ?

 
When your chosen developer hasn't confirmed the requirements although has accepted the job and is now well overdue
 
You can start an arbitration: https://www.mql5.com/en/job/rules#part_V
Rules of Using the Freelance Service
Rules of Using the Freelance Service
  • www.mql5.com
Rules of Using the Freelance Service: general provisions, execution of orders, payments,
Reason: