I cant login to my O2 app, and my money is just being taken away

I have been going through problems with my O2 app for 3 weeks now. Firstly it started with me buying 20 euros of credit on the app and it didn’t reflect into my account. I tried to go fro the hotline, but without credit, they dont attend me. Not even in emails. Then I bought my credit in the supermarket, 15 euros, it reflected after two days, then I bought data but it didnt reflect and the credit dissapeared. I tried to go to the O2 hotline but they didnt help either. I have prepaid.

How can I solve it?