Q: I didn't approve a purchase made by my child, how do I cancel the purchase and get my money back?

For responsible parenting:

iTunes Store: About In-App Purchases

          http://support.apple.com/kb/HT4009

iOS: Understanding Restrictions

          http://support.apple.com/kb/HT4213

You can ask here:

iTunes Store Support

http://www.apple.com/emea/support/itunes/contact.html

My kids played dragon city and thought it was free now I am receiving receipts for over $300 worth, how can I have my debit card credited and the charges reversed? I am so angry that was all the money I had in my account and I needed to do something with it! Please help

Many games are free for the base game but make money by having in-app purchases for levels, "coins", and such things. Follow the instructions Hackintosh posted back in June to prevent it from happening again and for contacting the iTunes Store. Refunds are not guaranteed, but you can ask.

Regard.