Thanks for choosing Apple.
Dear Customer,
Welcome back to the iTunes Store Customer Support. My name is Kumar.

I'm sorry for the delay in getting back to you. Thanks for your patience.

I would like to inform you that after reviewing the circumstances of your case, we determined that issuing you a refund for your unintentional
purchase of "iTunes Match" is an appropriate exception to the iTunes Store Terms and Conditions, which state that all sales are final. In seven to ten business days, a credit of 24.99 USD should be posted to the credit card that appears on the receipt for that purchase.

The iTunes Store provides a warning message that asks if you are sure that you want to buy an item. This warning can be turned off. If you would like to make sure that this warning is on, you can reset the warnings in the iTunes Store by following the instructions in this article:

Resetting iTunes Store warnings
http://support.apple.com/kb/HT1734

Additionally, you can make modifications on certain devices that will prevent them from making purchases:

iOS: Understanding Restrictions (Parental Controls)
http://support.apple.com/kb/HT4213

I hope this will resolve your issue.

If you have any further questions, feel free to contact us and we will be happy to assist you.

Have a nice day!

Sincerely,

Kumar
iTunes Store Customer Support
http://www.apple.com/support/itunes/ww/

Please note: I work Tuesday - Saturday, 11:00AM - 8:00PM CST