It looks like cex are rigging their own market.
Proof-
Users cannot buy ghs for less than 0.0001 btc, yet a large buy has been put on at 200 satoshis.
This is playing their own market and possibly illegal.
try to ask to their customer service, probably there is a special offer for who buy good amount...
Maybe you need only to ask for a "special prize" like if you buy a mining equipment from their site.
As far I know it's not illegal "modify" their own market, especially if already stated on their TOS.
