Finally check reviews on Google if there is nothing to find there, they may be pretty new or simply not worth to move forward with. In addition I would give them a phone call, if you can't phone them, forget it, what are you going once things go wrong!
this is of course not acceptable, do I need to say more?
As per the webpage, they've been since 2013, The Mail Box is for Hauteville Trust (BVI) Limited, a fiduciary service offering company incorporation and management services.
There are some casinos and trading web pages offering it as a payment service, but I wouldn't really want to trust those sites...
the thing is they don't really show their company incorporation name, so it's hard to search for any info.
exactly why I would avoid them and stay far away.
Alternative, ask them for the legitimated company data and what company they are registered with at Visa, if you want to spend that much time on it....