Not sure about the lease, but i was in the same situation. I didnt bother telling the landlord because i know their "spray" wouldnt do anything. Throw out your mattresses. There is really no way around that. I threw mine away and "bombed" the apartment (with those cans you can get at walmart for bugs). I left for 24 hours, came back and all the bugs were dead. ugh they are disgusting....good luck