how to fix my ADP 8242 Diplomat Dishwasher?

just moved into new house;no manual with the ADP 8242 Diplomat Dishwasher. Used it a few times topped up salt/rinse aid and used reccommended detergent etc. now the thing won't play!!I dont think the water is reaching the hottest temperature and it beeps intermittently and i have to switch it off after about 2 hours of perseverence and do my dishes by hand!please can you help I don't want to give up!!!