how to get refund from freelancer and hire a new freelancer ?

 
I have Posted a job on mql5 Freelance section over a week ago.
provided clear requirements and instructions on what I need, and asked him if he understands the requirements completely and he said yes.

the job was supposed to take only 1-2 days and freelancer agreed to that timeline and agreed to all the requirements.
he delivered a testing ex5 file within 2 days and when I tested it on my side it was nothing like the requirements I mentioned.

I requested him to fix the issue , and make sure that its working exactly as mentioned in the requirement document , and if something is unclear about the requirement document please let me know so I can explain.
Next day : He delivered another testing ex5 file and he has fixed the issue and told me everything is working , but now another issue popped up, I requested again to fix the issue and asked him to make sure everything is working before sending me the test file.
Day After that: he delivered a test file again and told me its 100% working , he fixed that issue , but a new issue popped up. I again requested the same thing and kept asking him to make sure Everything is 100% complete before sending me the file, however he has constantly failed to provide me a 100% accurate and complete EA which works based on the specified requirements in the document.
its been constant back and forth and he is still unable to deliver an EA which works correctly.

Now its been over a week and I dont think he can deliver the job , even if I ask him to fix current issue I am sure a new issue will popup (because of the pattern so far) 

How can I get the refund and use the money to hire someone who can actually get the job done ?