Automatic switch from "O2 Loop" to prepaid deal never happened

I bought the 14.99 euro prepaid card (special offer), which said that I would start with the “O2 Loop” account but automatically switch to the 14.99 prepaid tarif once I topped up that amount. However, it’s clear that it never switched, and now with 1.5 weeks left in this 4-week deal it’s asking me to top up my account for more data! (I also can’t make phone calls outside of Germany.) How do I get the account to acknowledge that I got the special data deal?

Edit by o2_Manuela: moved to English o2 Community: Mobile