Q: Redeem not showing balance

Restart your iPad.

1. Press and hold the Sleep/Wake button until the red slider appears.
2. Drag the slider to turn your device completely off.
3. After the device turns off, press and hold the Sleep/Wake button again until you see the Apple logo.

Then check the balance.

Help here >  See your iTunes credit balance

Hi,

You need to contact Apple directly > Contact - Official Apple Support