Horrible at AVIS - never had such a bad experience with a car rental

My expectation was to receive what I ordered as I got a confirmation from AVIS about the availability. When arriving I was informed that the only car available would be a FIAT - which was nothing like a SUV car (Jeep). As I received a confirmation letter, I did not surch any further. And that is probably the "trick" that they play with the customer. When you arrive in the morning you have almost no other option but to take what they "offer" you. What can one to - ofcourse I would like to walk out, but then you have to start checking other options, and that would probably take many hours - and then the day would be ruined. I know that this type of car (FIAT) was not the same price category. I was not offered an upgrade /the offered me a VAN - which I did not accept/. I was not offered a "good deal" if I would accept the FIAT. I asked for Mercedes cars they had (2 ea) but they were not willing to upgrade me - asking for more than double the original price for the SUV. /I saw only four cars, FIAT and two Mercedes and a Van/. I have never experienced that a rental would not upgrade a person when the promised car is not available. I was then offered a Volvo V60 - which I had to accept as I was not offered anything else close to what I ordered. I was informed that I had to wait 10 minutes for it. It turned out that I did not receive a car until more than one hour after arriving to the rental. No "sorry" from the staff about all this "blunder" on their behalf. Just stating that the "computer" sent out the confirmation - like AVIS was just "free" therefore! (The person servicing me did not speak English - which was not helping, but one can of course not expect that at a small local rental, and that was not any issue). The car had not been washed - it was dirty inside/out. The car was "ok" though, but not a SUV as called for. This was not a good start on the day for me.