I don't know who those guys are but if they refund 11 btc they cannot be a scam, can they?
The first few trades go all right (I've made a few), but then they stick you after the fact. What happened to me is I sent 1 btc and before receiving payment, I sent the other btc. They said this caused a "merge," which is absolutely absurd because bitcoin doesn't work that way. They then prompted me to send 2 more btc because it would "fix" the issue (if you need proof, I will gladly screenshot the email upon request). They said it would take a week to resolve the issue... This was nearly 2 weeks ago and I haven't heard back since, after multiple emails.
Look, try it at your own risk, but if you're looking to donate bitcoins, I'm more than ready to accept.
Also, try calling the number listed on their website, like I did. It is a REAL ESTATE company, not affiliated with btcpromo.net at all.
Please, for your own sake, do NOT send money to these frauds. They are either scammers or selective scammers.