Auto debit cancellation

I applied for portability and and for that it require 6,66 euro credit but everytime i credit balance it direct cut for plan i have already existing 9.99 euro plan still they direct debit without permission so ho i can send kundigung with proper creadit. 

Now i lost so much euros please help me as soon as possible. 

Thank you,

Jay Sukhadiya. 

Edit by Katy: moved to English o2 Community Mobile