Refund for double payment on app

Today, I credited my balance with 20 euros but didn’t saw any changes to the amount in the app. Although I received the sms. Then I re-credited my account with another 20 euros and then it added only 20 euros and package activated automatically without my consent. Overall I’m charged with 40 euros. I was aiming for 20 euros prepaid package. I want a refund of 20 euros as they didn’t showed in the app after i credited them. Your sms service is not synched with the app creating confusion for customers and wasting their precious money and time. I’m facing this issue for the second time. This time I need a refund it is a problem with your system, and it made me recharge my account twice wasting 20 euros of my own money. Could someone please help me.

Edit o2_Bianca: Moved from Mobilfunk Vertrag&Tarife to English o2 Community mobile