You top up 100 SEK. You buy a 30-day Surf package for 95 SEK (e.g., 5GB). Your remaining call credit is 5 SEK. You use all 5GB data. After that, data costs 0.95 SEK/MB from call credit until you refill.
For now, however, the classic saldo system remains robust. saldo comviq
If you are a heavy internet user, raw saldo is expensive. A single MB without a package costs roughly 0.50 SEK – that is 500 SEK per GB! Instead, use your to buy a Surfpaket . You top up 100 SEK