Sometimes due to various reasons a purchase does not get completed but the amount has already been deducted from your bank account. This is usually followed by a receipt for 0,00 from Google Play Store or iTunes. If so, rest assured that the amount will be credited back to your account within 48 hours.

Should you have any further questions on the matter, please do contact Google Play Support at https://support.google.com/googleplay or iTunes support at https://support.apple.com/contact directly.