Car brand justified by technical defect – downgrading in liability?

Hello, I’m new here in the forum and have a question about car insurance! In December 2007 my vehicle burned out completely in my parking lot directly in front of the house. The DEKRA expert commissioned by my insurance company attested a technical defect to the battery (at my Audi A6, year 1996, at the rear left under the rear seat) by a mass closure at the plus pole after the central locking operation. The vehicle then completely burned out – total damage. The fire damaged a carport and a car parked on the left side of my car. I logged off my Audi shortly afterwards and let the contract rest until today. The developed SF-classes remain with me, so the information of my insurance then, at least for 7 years. The damage was settled as partial cascade damage – to my knowledge, after such events no reclassification in the SF takes place. Now, one and a half years later, I called this week at my Car insurance to register my partner’s car for me, because I have a better SF-Class (2 x 22) to save money. The nice lady on the phone told me that I had been reclassified in the liability of SF 22 to SF 10, because the insurance paid out a service to me (the residual value of my Audi). To my knowledge is a fire damage (also caused by force majeure – technical defect according to expert reports) with all damage regulations, which Dami Is the reclassification of liability justified in this context? Who can give me information about this here or has had similar experience with his insurance?