Connection financing, KSB resisted, now invoice from the dealership

Hello. The following mysterious case: car re-purchased and financed. Now after the end of this financing the balance was financed again via Skodabank and the car dealership. I revoked the credit protection letter (ratenschutzversicherung) for the closing financing properly and in due time. The revocation was confirmed by the bank already 2 weeks ago. And now a letter comes in from the car dealership: you want a close 250€ risk flat rate because the KSB was terminated prematurely. The KSB has been revoked, not canceled. What risk should the dealership have by the revocation? Is something like this known or already happened to someone? Is this legally OK? For me this sounds easy: “I try to get the lost commission for the KSB in otherwise!” Can of course also mislead me, then I swallow the toad and pay that. Is after all only eta 1/6 of the complete cost of the KSB. But only if I have to. Thank you for your help and opinions.