You can find a reseller to purchase a voucher.
Experienced downloaders know about this, and it's the reason that uploaders cannot get sales directly.
The fact is
make it easier for the downloaders to
get more sales, not complicate it having to read the terms of service or find a reseller. Such complications makes people mistrustfulness in the file hostings companies (Uploadable in this case) and then we don't get sales.
You are right, but I have no idea because Jo is reluctant to talk about this.
On downloader-oriented forums, users are warned that Uploadable is an auto-recurring filehost and the cancellation is very hard.
People who complained about it usually knew they have to send mails in order to cancel it, but their mails are usually ignored or handled very slowly (after they are rebilled).
Therefore, downloaders concluded that they should find resellers to buy vouchers or use other filehosts.
In fact, new sales are usually contributed by stupid newbie downloaders, but rebills are contributed by hardworking uploaders because they make downloaders stick with them so that downloaders who tried Uploadable first don't need to try other filehosts.
Users on my site often choose depositfiles links even though we always put Uplodable links to the first place.
Whenever a depositfiles link is dead and the corresponding Uploadable link is alive, users often decided to report "depositfiles link is dead" instead of downloading from Uploadable.
Maybe Jo still doesn't believe they have any competitors, but I don't think so.