Actually, I am a freelance writer and offer my services through several writing sites. While I cannot speak for other writers, I have
never had any customer complaints. My policy, as a writer, is to maintain constant contact with my clients via either e-mail or telephone.
Many services prefer that the client and writer not have direct contact. Often this is the writer's stipulation, not the service's. As I often edit other writer's work, because I am not qualified to write dissertations, I have found that PhDs tend to be rather prissy and don't want bothered by the client.
I can say that the sites I work closely with (especially concerning dissertation orders), when the writer prefers not to maintain contact, they have seen that this makes the client nervous and seems distrustful. As such, I, as the editor and coordinator, maintain contact between the writer and the client.
If a site you are interviewing for writing services does not offer constant contact - move on to the next! Here is a list of the sites I work with as a writer:
// removed per author's request //I can personally guarantee your satisfaction if I am involved with your order. It is impossible for me to speak for the 100s of other writers associated with the site. But I can say that I have always been paid for work performed and do not even submit for payment until the customer is 100% happy.
Hope this helps!