http://armory.warmane.com/search/Sixoo
There's 2 characters with the same name. You've been sending gold to the lowbie one.
Contact staff via general ticket or [email protected] so they can help you.
You won't get the gold that you sent already back though.
All the gold you've sent is on the lowbie toon's mailbox. You can ask the dude politely to send you gold back, if he's an honest person he'll do it if not, well, tough luck.
I don't know exactly how, but it happens. I think it has something to do with characters being on trade so they "lose" the name even if they still have it but don't quote me on that.
It's a known issue that should be sorted out soon. I've been told that you can open a support ticket from My Account -> Support or send an email to [email protected] to get items back in this case.