cancelling the loop

Hello
Since there is no help in english for the hotline, which is absured, maybe here...

I dont use anymore the prepaid card, and i even dont have it anymore. I dont use it since march and somehow the tariff is a loop which i never ordered, and it takes of me every month since then 20€.
I must cancel this somehow and is it possible to get a payback? Since obviously you can see there is no use at all of the company.