Dollar Rent A Car Charges - fines Denver, Colorado

I rented a car at Dollar in March at the Denver airport.  At the counter my husband and I discussed putting him on as an additional driver - we decided not to.  When we were asked to sign the man behind the counter asked my husband to sign and I said wait what is that for? The man behind the counter said to add my husband as a driver.  I told him we decided not to do that.  When we returned they charged us for the additional driver so we went back to the counter.  They said they could not do anything about it because my husband had started to sign for it.  He had the first two letters of his first name on the contract.  What a rip off!  
Now a month later we got an invoice from Dollar in the mail for toll charges for while in Denver.  The catcher is this.. Denver has done away with their toll booths and so they charge your license tag.  That is all fine and we knew this ahead of time even asked the people at Dollar about it.  On our bill for the tolls they are charging us an additional $25 a toll booth for the toll charges which totals an added $100.00!  There are no toll booths so how were we to pay otherwise? I even asked them if they rented transponders as I had been out to Denver before when they did rent the transponders.  What a rip off!!!