Not sure if it's a scam, but I bought some cheap XRB there a while ago. I was trying to log in just now, and apparently their website has vanished completely. 
Their stats on CoinMarketCap also haven't updated for 3 hours. I'm willing to accept my losses, but if someone is actually able to reach their site, please post below.
As shitty as an exchange Mercatox is (and boy, is it shitty, I have had deposits "vanish" and they ended up not being credited to my account), I don't believe they are a scam (or at least I hope not, who knows).Their stats on CoinMarketCap also haven't updated for 3 hours. I'm willing to accept my losses, but if someone is actually able to reach their site, please post below.
They disabled their website due to a large DDoS, see https://twitter.com/MercatoxCom/status/948143881467645954
There was no DDoS attack.
They came back and said it was registrar related - meaning they didn't pay their bills for the site. Which is bullshit. Beyond amateur actually.
I have 5mil KIN in there and 400 XRB - hopefully it comes back but it doesn't look good no matter which way you slice it.
There are two scenarios that will play out
1. They ran off with all the profits from XRB - probably because they over sold their XRB inventory and just pocketed everyone's money. Let the site expire and are already halfway to Bangkok.
2. They purposefully slowed down XRB withdrawals because of the Binance vote and now put the site into maintenance mode. Once Binance comes live - many people will move their XRB to Binance which would lose them tons of value despite the fees they collect. Also purposefully bogging down the site with issues will allow for the price of the coins to stay - if you look at CoinMarketCap the price for XRB is still at $35 and it was last updated 9 hours ago. The price on BitGrail is $29 so you will see arbitrage happen vice versa which brings in more value and users to MercaTox.
I am really hoping it is #2. At least this way we know our funds are there.
However - with their track record for the last 3-4 months, it looks more like it's #1.
Please pray for us all!