Can I cancel a payment that I made?
If the transfer is still pending, you can cancel it at any time:
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Go to: 'My Account' > 'History' > click cancel next to the respective pending transfer.
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If the transfer is completed, Moneybookers cannot reverse the payment anymore. We recommend you contact the recipient directly and make arrangements for him to return the money to you.
fra:
http://www.moneybookers.com/app/faq.pl?gid=2&qid=205