We rented a car from avis on line for vacation in dominican repablic from 09/22/07 to 10/6/2007.The daily rate for car was 21.78 for 14 days.Total price of 304.92. We also purchased rental car damage protector plan for 135 dollars which we payed right away on line. Total price combined was 531.38.When we came to return the car at the end of our vacation we were told that the charges are 788.15 dollars. We presented a copy of our contract with confirmation number that we printed from the computer but could not get any explanation of discrepancies. We were told that the manager was not available at that moment and that we had to wait. However,we had flight to New York that would not wait. We refused to sign the charge reciept for 788.15. When we came to New York, we called AVIS with complaint. They investigated the case and sent us a copy of the contract, which allegatelly, my husband signed (4 pages total) and only one page has my husband's signature on. ... There is no total amount that would be charged. There is rate per day(21.78) and insurance rate per day without total amount written.This was only page of contract that we have been ever presented. We assumed that the charges for insurance were those that we already paid (135dollars). We have never agreed to purchase any other insurance.