I've bought 3 accounts, and they've all been lost/recovered somehow, I don't know why. The most recent account I bought was linked to my e-mail and Jagex says it's the wrong e-mail so I can't recover it. $150+ wasted. gg
Did you use paypal as your payment method? If you did, you could try to charge back but there's no guarantees.
This really should go somewhere in a sticky:
Even with the registered email set, the original owner can still easily recover. He either sends an email to jagex and waits for 2 weeks or so.
they have 14 days by email to recover it back and sayu it was a mista/ some 1 hacked you email sorry to hear you got scamed dude if you ever pay high for a account get a omm to hold for 14 days
@Brendan, true, but that thread doesn't really give details. Maybe that's for the best though, it might just encourage people to recover the accounts they sold.

