I don't see the Mac App Store trying to recharge you for a previous purchase. The alert is telling you that something was amiss with a recent purchase. Apple has not been paid for that purchase because there may have been a problem collecting from whatever was your payment method. Your account has been frozen by the system until you resolve whatever was this recent issue and you will not be able to update, redownload or buy anything.
Contact Mac App Store Support to resolve the issue.
http://www.apple.com/support/mac/app-store/
Late 2012 Mac mini, OS X El Capitan 10.11.5 beta 4; Watch, 38 mm silver AL, Watch OS 2.1; iPad Air 2 & iPhone 6+, iOS 9.3.2 beta 4; Apple Airport Express