Dishonored guarantee

My Bosch vaccum cleaner stopped working after 364 days just short of one day from the one year guarantee and 10 year warranty on the motor. I was told the motor burned out, but Bosch never gave my any official answer : no Email, no message whatsoever- just a verbal answer to tell me that they will not honour their guarantee due to the fact that one of the inner filter was not clean. I found this unfair as the motor is protected by a thermo switch. They should have honoured their guarantee. I would like to know what to do to take it further.