I want to tell you about my horrible experience with this company, so hopefully I can save a few of you from the nightmare their customer service has been.
I ordered the V2 Pro Series 3 as soon as it came out - and not just the device, but 5 liquid carts and 5 loose leaf carts. After just a few weeks most of the liquid carts started leaking, pouring out juice from the bottom. I switched to just using loose leaf with the unit. Then, maybe 3 weeks in, the unit will not even keep a charge for more than a few minutes. Light goes red after just a few puffs, after hours of charging.
I tried to contact customer service both by phone and email. 5 emails later, 3 phone calls, no response or return calls. I tried their chat function on the site and FINALLY got someone to agree to send me a working unit. Almost two weeks later, a package arrives - and its a cheap little junk battery for their non-series 3 regular ecig line. Worse even, I start getting threatening emails from them almost immediately that they will charge me 60$ for this battery that isn't even for the series 3 if I don't immediately send them back the non-working unit.
So, I HAVE TO PAY to send the wrong battery back, and then they disappear again. They haven't answered another 5 emails, phone calls go unanswered, and I'm back to square one.
5 loose leaf carts I cant use, leaking liquid carts, a battery that wont work and they refuse to replace, aggressive and harassing emails that they will charge me for parts that I neither asked for and don't even go with my unit.
I would highly advise you stay away from these people until they realize the value of proper customer service, and have a reliable product.
I had the same battery issue with the replacement that I was shipped after my first one self-destructed. I then had an issue when I moved and they twice shipped replacements to my old address rather than the new one. In the end it was made right, though. Finally got a working replacement and haven't had an issue over the past month.
They can definitely be a bit hard to get a hold of sometimes. I haven't visited their forums yet, though.
As for the leaking carts: I still have the same problem, but find that it can be managed. What I do is whenever I'm going to refill a cartridge, I take a wadded up piece of tissue or paper towel and press it against the bottom for about 15 seconds at a time, multiple times. You'll see the loose juice seeping into the paper. I do this until I can press it against dry paper and nothing comes out. Then I unscrew the mouthpiece, dab the inside of both pieces with the paper towel, and then blow into it from both ends while holding the opposite end against the paper.
I then fill the cartridge and finish by carefully dab the opening to the cartridge with paper once again to make sure it's dry before screwing the mouthpiece back on. I find that this process makes the cartridge "fresher" so that leaking doesn't occur again for a while, not until it's about time to refill anyways.
It might sound like a lot to do. But with 4-5 cartridges with different flavors in rotation like I have, I don't have to refill very often and when I do it only takes me about a minute per cartridge all in all.
I do wish the cartridges were more hassle free, but they are only $5 and I'm still pleased with how easy it is to switch between cartridges thanks to the magnetic system that I'm still happy enough with the V2 Pro S3 liquid setup overall, for the money. I've been vaping all day long with it for months now.
I've finally got my first herb cartridge on the way right now. I'll let y'all know what I think once I get to spend a few days with it…
I noticed that the Series 9 isn't advertised anywhere on their website anymore. The Series 7 is still listed as coming soon, though.
Edit: Forgot to mention that I've found that they don't like to charge from the high-watt (12W) USB ports I have in my car. I get the early green light and short battery life when I try. If I charge it low-and-slow from my laptop, it works correctly.
(now I just need to cut out the 1 or 2 a day 
