I've been using BlackVPN for about 2 Weeks now. Since then I have discovered, that the Login worked flawlessly for the entire time. The download speeds vary, sometimes they tend to be very slow, other times its pretty good for a vpn service. I use the usa login. Services like Pandora, Hulu, Netflix work suprisingly good, so overall, i can't complain, especially for the very low price of 5€/ Month, which can be paid easily via PayPal.
I use the BlackVPN service on 2 Macs, an iPhone and an iPad and it worked extremely well on all devices so far.
I didn't had to contact the support until now, so I can't say anything about that.