Corrosion on the chassis

Hello Honda fans, since I have problems with the warranty claim with my contract workshop, I turn to you. At my Honda C-RV (bj. 10/2007, reimport from Denmark) during the repair of the air conditioning at the Honda contract workshop in August 2010 rust was found on the chassis (see pictures). The air conditioning repair was carried out free of charge (guarantee). I then asked the car dealer to eliminate the rust damage on the chassis via warranty. I received from the contract workshop on 30.3.11 the rejection of the rust removal. Reason for the rejection: Import vehicle. The service was always carried out in Honda contract workshops. Is this rejection justified and can you tell me your experiences? Thank you for your efforts.