You need a zero account balance and you need to cancel all your subscriptions. If you have cancelled all subscriptions, but some haven’t expired, contact iTunes Support. You need a valid credit card issued by a bank in the country the store is in and you need a billing address in that country. If you have an account balance, either buy something more expensive and pay the balance with a credit card or contact iTunes Support and ask them to zero balance your account.
Purchases - View, change, or cancel your subscriptions.
Purchases - Subscriptions not billed through Apple
Region - Change your iTunes Store, iBooks Store, or App Store country or region.
If necessary, contact iTunes Support. Follow through the screens to get a chat or telephone option.
iTunes Support – world wide
Apple Support schedule phone call
Some other things you can try. Do you have access to another WiFi network where you can try? That has worked for several people.
Try a restart.
Restart your iPhone, iPad, or iPod touch
Try a forced restart.
Reset Device.
If necessary
Hard reset.
Do a backup and try a factory reset. Then restore from your backup.
Restore to Factory setting.
Backup - Restore your device from an iCloud or iTunes backup.