Alamo Rent A Car

I made reservations with Enterprise rental car who I always rent from, but now found out they are partnered with Alamo and National. I reserved a premium car unlimited mileage 4 daily for est. $55.00/day total $293.14. I met with a Juan who mentioned he was new and he assisted me to rent a car. I did see a dodge charger that I thought was a premium car that would fall under the same agreement and cost, which Juan rattled off two hundred and something dollars coming to three hundred which was about the total of the agreement, so I figured everything was good and just signed electronically. Juan never said that he would need to cancel out my Enterprise agreement in order to get the dodge I thinking, is what happened and I also think there may have been a language barrier or miscommunication because Juan never said anything about an enormous increased charge like 1,300 more! I didn't realize until bringing the car back and looking at my email that I saw an Alamo agreement. I was completely dumb founded to realize this and could not understand what happened if I had a Enterprise agreement #[protected] Alamo agreement #[protected] case #[protected]