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I am sorry to hear that your order was cancelled. If you don't see the transaction on your PayPal account, this means that you may have completed the payment via Guest checkout. Firstly, I would recommend contacting the merchant to request a refund. The amount would be refunded directly to the funding source used for the payment, even if you did not log into your account to make the payment. If you don't receive a refund, you can contact our Customer Service and request that an Item Not Received case is filed for you.
If you want to contact our Customer Service, you can click ‘Help & Contact’ at the bottom of any PayPal page to see which options are available. You can also contact us on Facebook (www.facebook.com/PayPal) or on Twitter (@AskPayPal).