Cancel mobile subscription because I moved abroad

I have been trying to cancel my subscription for MONTHS. I was studying in the Netherlands but I have moved out since July. I submitted proof of finishing my study but that got rejected. I have been living in Germany since november and sent the anmeldung (proof of registration at an address in Germany) AND my employment contract with a company here in Germany multiple times to an e-mail address provided by one of your customer service agents via the phone, but i haven't received a single reply. It has been way over a month since I submitted them, it should be enough proof that I no longer live in the Netherlands. I have called multiple times your customer service line, someone told me the contract was already cancelled but I just received another charge???