o2 charges me 0,99 dayflat instead of renovating prepaid plan

I have an active o2 prepaid S plan.

On 21 May, the dayflat of 0,99 was discounted from my credit even when I had the automatic renovation of my plan activated and the sufficient credit to do so.

I don’t understand why I was charged 0,99 for the dayflat rate instead of my plan being renovated. I had 10+ euro in my credit for one more month but now after being charged the dayflat rate I don’t have enough credit for the plan. It seems like the dayflat charge was processed before the automatic renovation, this shouldn’t happen. 

I would like to get my euro back in order for the plan to be renovated. What can I do?