Purchase Could Not Be Completed

This is a user to user community forum. We do not have access to your record, so cannot tell from your very brief description what the problem may be. There is likely a problem with your payment method. But please contact Support. They should be able to help you.

To contact Support, do this: 

1. Click on this link --> Choose your country or region - Official Apple Support  

2. Select your country

3. Select: Billing & Subscriptions

4. Select: Subscriptions & Purchases

5. Select: Update payment method

6. Select a chat session or a phone call.

Copied from iTunes support - Apple Community