I purchased a whirlpool water

I purchased a whirlpool water heater(model #E2F0LD035V ) 1/30/08. Professionals installed it in March.The building inspector will not sign off on permit because it does not keep hot enough temp. (after about 5 minutes temp. drops 10 or more degrees. Plumber has replaced elements and one thermostat.The electrician called service number and hold 40 min. finallly hanging up( charging me for this time). I've called service # 4-5 times each person telling me somthing diff. (when i got thru) I want to return it!!!