Change of Reservation Drop off

I emailed Carrentals.com (since there is no way to contact them by phone unless you are willing to find the number through the internet and then wait on the phone for more hours than I could) to simply change the drop off from San Fran to LA and add one more day.  So they cancelled the reservation but did not change it for me.  So I lost the reservation and that type of car.  Not only did they not apologize, their emails were indignant.  I will never use them again.