Do not pay immediately and do not sign a cease-and-desist undertaking — the texts are often excessively broad. A legal response within a short deadline is essential; a solution with a narrowed scope is usually possible.
Silence is the real risk: ignore the deadline and the sender can move straight to a court injunction (einstweilige Verfügung) that costs far more. The usual answer is a modified cease-and-desist declaration — narrowed to what you can actually accept, with a capped penalty — filed within the deadline. Do not sign their broad wording as sent.
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