Thank you for contacting iTunes Store Support, my name is Mon.
I understand that you couldn’t change the country of your iTunes Store because you still have store credits in your account. I know how eager you are to have your concern addressed. No worries, I have looked into this for you and provided information below.
In order to successfully change countries on your iTunes account, you'll need to spend any remaining store credit. Store credit balances can consist of balances from iTunes Gift Cards or iTunes Gift Certificates, or song credits issued by iTunes Store Customer Support.
To see if you have a credit balance, please follow the steps in this article:
https://support.apple.com/en-us/HT202359
If you are unable to completely deplete your store credit balance because it gets to an amount that is less than the price of one song, you can give me permission to remove the remaining balance in your reply to this email. Please reply back with your permission to remove the remaining balance.
Once I have received your reply, I will remove the funds from your iTunes Store account, allowing you to change the country associated with the account. Please note that the funds I remove from your account will not be returned to you once you have switched countries.
For your reference on changing the country of your iTunes account, please follow the steps in this article:
https://support.apple.com/en-us/HT201389
For more information on changing countries, please see this page:
https://support.apple.com/en-us/HT204447
I look forward to hearing back from you.
Sincerely,
Mon
iTunes Store Customer Support
http://www.apple.com/support/itunes/ww/
I work Monday to Friday, 8AM to 5PM, Central Time.
Thank you for allowing me the opportunity to assist you.