[Effendi]

@ ca-uk: you've been ripped off by the Wind dealer. They took you 30 euros for the sim-card (10€) plus a 20€ refill. But they didn't refill you...
Then you did the wrong thing (my girlfriend did it too a few days ago...): ALWAYS WAIT for the activation SMS before using data. So you lost your 5€ of credit. At that point you were at 0€, so you had to refill. You refilled with 15€ but you needed 20€ for the data option so you had to refill again and you are now with 10€. All correct.

@ cregaune: Mega No Limit, as all Wind data offers, recurs automatically every 30 days. It seems yours already recurred so it tried to take the 20€ from your credit, but you didn't have enough, as it happened to ca-uk too.