[Effendi]

You used data before the data option was active, that's the reason why your credit quicky went to zero and then you had to refill again...

Wind card include 5€ of credit, while the Mega Unlimited option needs 20 to be activated. You had to first refill with at least 20 euros and WAIT for the SMS confirming the option was active. You didn't do so, so you used your 5€ +refill using data (2€/hour) and when the option was activated it took you the remaining credit leaving you with a DEBIT of about 6€. When you refilled again (with 10€, I suppose) your credit went up to 4€ and the option was finally active.

Anyway, to register on wind.it you have to enter the codice fiscale exactly as it was created by the dealer you bought your card from.