He did not send the account after I paid him!

That's why there is the possibility for escrow:
https://bitcointalk.org/index.php?topic=133931.0You are here four years, so you should know this.
But I surely hope for you that there is a misunderstanding and this will be solved soon.
BTW Even when you receive the account for the price you paid, I think you're scammed. The price is just too high.