AVOID Gold VIP Transport Service, don't buy a ticket from these scammers!
I did a terrible mistake and bought a ticket from the to a sleeping bus from Siem Reap to Sihanoukville. They advertised their buses as amazing VIP buses with great sleeping beds and extra services like free Wifi, free water and so on.
Once I got the bus it turned out that I (as well as all the other passangers) was scammed. The bus was NOT a sleeping bus at all. We tried to complain but Gold VIP guys didn't care that at all and suddenly they didn't understand English anymore. It also turned out that they don't provide their "extra services", none of them. The only "service" was that we were forced to watch (or at least listen on maximum volume) some soup oper in kmehr language.
But the worst came just after that: it turned out that the bus was NOT a direct bus to Sihanoukville as it was advertised but we had to change our bus two times, both of the times waiting 2-3 hours. So finally the whole trip took 15 hours (instead of 10) and we had to spend this amount of time in 3 different smelly, dirty and overcrowded buses, in one case without air condition.