Why would a dishwasher filter

Question

why would a dishwasher filter split/break in a meile dishwasher that is not even 3 years old. i have been told that it is not under warranty and that i have to pay the $580 bill even though i feel that it must have been the dishwasher as the maintenance man said that it would have been nothing that i have done. i have had other less expensive dishwashers that lasted a long time. i am going to write to meile and see what they say. what do you think? should i persue this as i feel it was a fault in the dishwasher not with me. thank you very much for your advise. sharon