But that isn't the whole story because of their problem with the billing system there is a window of up to 20mins before the billing system see that your cap has run out and your connection gets slowed to dialup speeds. That means users can still surf the internet at full speeds until then.
Now, if you don't buy another data block, Slingshot writes off that data but if you do buy another data block then Slingshot bills you for the data you used before their billing system capped you to dialup speeds.
That means that a user can buy a data block only to find most of it gone before that get to use it.
That seems unfair. Users who don't support Slingshot by buying more data blocks get it for free, while the users who do buy more data get billed for it.
Slingshot know about this issue but have nothing on their website or help section to explain it.
It was asked about on Slingshot unofficial forums and a couple of staff where not so helpful, one describing the customer as 'stupid' and the other posting the picture below outlining the issue.
Just bought 6gb of Data and it gets used up in seconds??

I wish Slingshot would fix this issue, all they would need to do is when the account gets closer to using all it's data, that they test the data left more often than every 20mins.
Or they could write off that data used, like they do for the people who don't buy more data.