Hi @MartaMD, 

welcome to our English community. 

Would you like to ask for the cancellation of your prepaid-card, or do you have another number in mind? 

If you like to cancel your prepaid-card, this is quite easy. The card deactivates itself after 6 months. The only thing that you need to care for, is to get the remaining credit of your card back. For this reason, just fill out the following form: http://g.o2.de/pre-auszahlung You will then receive the remaining amount on your bank-account. 

I hope I could help you with your request. Have a nice and healthy stay abroad. 

Loving greetings, 

Tobias