avis car rental omaha airport double charged for rental on 2 different cards. included ins. when declined as well as gps omaha Nebraska

I rented a car in omaha at the airport dropping it off the following day in chicago.  Imagine my surprise when avis gave me a  rate of $120 for less than 24 hours.  It was a Ford Fiesta at that.  The agent took my card and scanned it taking $362.74.  He then said it didn't take and he couldn't run it twice did I have another card.  

I gave him another card and he scanned it as well only this time taking $242.00 from this card.   He told me the car came with a gps I told him I had my own then he added insurance of $28 and I also said I had that as well.  He claimed his little box that I signed wasn't working right and rushed me thru the paperwork.

I left and went to chicago.  When I turned the car in after refueling it 5 blocks from the airport  the scanner wasn't working either.  I was asked for the paperwork  and I gave it to the return person he said my paperwork would be emailed along with the receipt.   One week later I discover charges of $600.

Their customer service not very helpful.  Refused to put me in touch with omaha manager said they have no way of contacting them. 

Beware of Avis.  They try harder to rip you off.