Sixt Düsseldorf Airport Added Insurance Without Consent

I rented a car from the Sixt office at Düsseldorf Airport from December 5 to 7. During the rental process, the customer representative confirmed that a deposit would be collected and refunded. However, despite my having clearly stated that I did not want insurance, a policy was added to my name without asking me or obtaining my consent.
I trusted a well-known corporate brand, but €127 was quietly taken from my account for an insurance fee I never agreed to — and I only discovered this after the fact. Having this charge added despite explicitly declining insurance at the outset left me feeling deceived.
I reached out to the company by email regarding this situation, but they did not even bother to respond. The complete lack of communication and the lack of transparency in how this transaction was handled have been a serious disappointment.
I am demanding that the unauthorized insurance charge added to my name under reservation/contract number 13284076 be reversed and that the full €127 be refunded to me immediately.