Posted on their twitter a while ago: https://twitter.com/Bulknews/stat...5140144128
**WARNING** There is an odd bit of text when signing up:
"You will receive a fixed amount of data per month for a reduced price (min. € 1,50) Left over data will not be transferred to the next month."
All the block plans state that. I am interpreting that to mean if you selected the option to automatically renew a block plan on a monthly basis you won't have unused "carryover" data added on to the next month. For example, if you only use 4 TB and pay for a monthly renewal you only get 6TB when it renews, not 6 more TB on top of the left over 2TB from last month.
If you do not select the auto-renewal then I'm fairly certain you keep your data until you use it up, at least that hows it worked when I had bought a bulk Black Friday block 3 years ago. Back then 1 TB lasted 3-4 months as a backup for the missing data on my slower Highwinds service. I did not have to pay a monthly fee to keep my account active.
Bulknews.eu uses Abavia/XSnews backbone so a nice supplement to these current deals:
List of backbone providers (it is best to have services from 2 different "backbones"):