Dollar Rent-a-Car fear my wrath

So we arrived at Newark Airport about 6:30ish pm on April 12. We took the airtran over to P2, where our rental car awaited. We went through the bru-ha-ha of obtaining our rental. It was late, and the sweet girl upgraded us to a convertible Sebring, which was nice. She asked if we needed insurance and, I must admit, as I was the sole driver I daresay we did. She advised us it was an additional $39 a day for this privilege. Needless to say I flinched when I signed the contract.
We drove up to my mothers house in Suffern to stay the night. Mom was out cold but we woke up Phil, who had endearingly fallen asleep in front of the television. Some things never change, bless him. We said our goodnights and went straight up to bed, since we were absolutely exhausted. The next day, mom was up waiting for us, tea and coffee at the ready, as Phil was out obtaining fresh bagels. It was a perfect morning, till I put my foot in it. As is my way, I started kvetching to my mom about the price of insurance yada yada. Imagine my shock when she advised that she had always kept me on her insurance. What a dear woman! No problem, I'll just call Dollar & have them drop it.
Oh gosh, it was bigger than I thought.
I was connected to a woman down south somewhere. I advised her I no longer needed the insurance and can she please drop it. "Sorry no" said she "This can only be done at a Dollar location". "Ok", I replied "Where is the closest location?".

"Newark"
"Oh God No"

She had to put her boss on because I was convinced there had to be another way than making me drive all the way back to Newark, especially as we meant to be going up to Kingston within hours, exactly the opposite direction. They continued to advise me the only thing I could do is go back down and sign another contract.
I was about to take off at that moment (7:40am) but mom had the wherewithall to make us stay so that she could call her insurance and make certain I was covered. Phil arrived back home whilst we waited, and so we had breakfast as I was slowly calming back down. I tend to get upset when it comes to my money, my time, and stupid rules and redtape.
We got there around 11am. Several employees had to "discuss" our situation before they finally decided to produce a new contract. They charged me for the day ($101, which was the day plus the $39 for insurance, plus fees & taxes), then they wrote up the contract for the remainder of the term.
"Wait a minute, this is for $270. My previous contract was for $270, I just paid $101, how can you charge me the same rate when I've already paid for a day?".
They began to talk about how they go by weekly contracts and this was the best rate they could do. We told them we didn't care and they best fix it right quick. They were able to locate a manager who broke down the contract to a daily rate, so we paid only by the day and not the week. Better. However, they were going to pull our free upgrade and give us another car. I actually didn't have a problem with this, since the convertible was a bit too small for our needs, but when they wanted to charge us $7 a gallon for the fuel we had already used, we told them they'll need to let us keep it at the same rate. They agreed, and we were on our way.
Next time, I will think twice about using Dollar. Sheesh. However, this chapter isn't closed yet. When we dropped off the car at 5am April 18 their computers were down so we couldnt finalize the bill. If they charge our credit card by any more than the agreed-upon sum, heads will roll.