Not a SCAM! I just unlocked my second phone with them and my phones where unlocked successfully. They just have so many customers so it takes awhile until they reply with a message. But it is a legit company.
It Works! Don't worry. Unlockriver is not a scam. At first I was also worried because they took awhile to send me the email with the unlock code. But I just got the unlock code and it worked perfectly! :)