Sentebits 

This is a fraud plain and simple. I was introduced to this company by a friend. I read through their website and decided to invest some money, approximately 1,000 EUR. After you create an account with them and transfer Bitcoin to your account you can monitor how it progresses day by day, so all seems in order. The problem starts when you want to cash out some of your earnings. Your withdrawal request remains pending for days and when you send emails to them you will get not reply. If you push them hard enough they will come back with some vague excuse and leave you in a limbo. They never sign their emails so that you do not know who you are dealing with.
Stay away at all costs. I have already reported this company as a fraud to ActionFraud.

This company operates through a scammer site. The site is supposed to be set up so that investors can see how their investments are growing on a daily basis. Even though the site itself is legitimate, the people behind it scam you into thinking they are looking after your account, only for the investors to find out much later that they cannot access their profits and cannot withdraw their funds. I was approached by a Mr Travis Von Hoopes through LinkedIn, who told me that a Mr Simon would take care of me. Mr Simon is not his real name. He poses as another Simon Heapes who is a gold miner from England.
I was scammed out of $6500. My account grew to $200,000+. They encourage you to take up a promo offer to boost your earning capacity. This again is a way for them to gain more money.
Their communication is really poor and you will become extremely frustrated by continuously trying to gain information on your account....
My account is still live at present, and I have given them an ultamatum, giving them plenty of time to send my withdrawal. Otherwise a Lawsuit will be initialised.
Invester BEWARE!!!