Accidentally order two plans instesd of one.

So I order my first e-sim thinking that it would arrive via email, instead of by post. Given my circumstances that I haven’t arrived in Germany yet, I had no idea. Thus, I made my second order thinking it might be a system error. 
 

Once I’ve arrived, I saw in my mailbox that I have received two! I immediately went to the closest O2 shop to cancel the second order. They did, and affirm me that I won’t receive charges. Since the e-sim was never activated no longer than 14 days. Fair enough. 
 

Just as I thought this is behind me now. I received the bill of two numbers still! I called the customer service, they said they will inform me after discussion with their within 24 hours. Sadly I never heard from them again, nor I can find a customer service email. 
 

What can I do :)