I am facing problem of payment not completed for my free apps

What is the text of the message that you are getting ? If it's telling you to contact iTunes Support ? If it is, and if you haven't done you, you should contact them (these are user forums) :

- go to http://www.apple.com/support/itunes/ww

- click on your country's flag (the country where you are, and which is therefore the country on your account)

- click on Contact Support towards the top right

- click on Get Help under 'Talk To Us'

Or use this form : https://www.apple.com/emea/support/itunes/contact.html