If the transactions are showing as completed then you would need to contact the merchant you paid and ask them to cancel your order and issue you a refund.
You can only cancel a transaction that has not completed and only then if the email address it was sent to is non existent ie wrongly spelt and so can never complete.
Advice is voluntary. Kudos / Solution appreciated.
Thanks, but what if the receiver claimed to have received money in a format of goods payment instead of friends and family, does that mean that receiver won't have access to such money?
If its marked as completed in your Paypal account then you have paid. The fact its pending on the sellers account is between them and Paypal. Funds for new sellers are held for 21 days but released more quickly if they provide a tracking number (delivery + 1 day).
Even if the funds were withdrawn to their bank account they are still obliged to issue a refund if they lose a dispute. The hold is to protect Paypal from bad sellers that refuse, meaning Paypal may have to refund the buyer instead putting the sellers account into negative until they pay Paypal back.
If they refuse to send item/service then you could file a dispute for non receipt. That may impact their paypal account in some way if they continue doing so.
