****** money and poor service

I haven't used my PayPal account in a year. Suddenly a transaction came through my PayPal and deducted R7 419,40 from my linked bank account. I reported this to PayPal as an unauthorized transaction. They said it was a valid transaction and refused to refund. They have no info for the merchant who took my money other than a Yahoo email address. I tried another route by asking them to reverse the transaction as i did not receive anything from the merchant. They said i should take it up with the merchant. I don't know who the merchant is. This is unacceptable, PayPal...