vehicle is running rpm's into the red before it shifts

Had several instances where we're driving down the highway accelerating to a crusing speed when the RPM's sky rocket and the car begins to shake and high pitched whine comes from the car. The gears will not shift the way are supposed to. We have had to exit the freeway, turn the car off and start it again to get it going. We have also tried pushing through it and it has worked a few times. This is insanely scary, since i don't want my enhgine to blow up because it's not shifting. We have also reported this issue to Karmart in Burlington, WA. (where we purchased the car), to Dodge/Chrysler and to the finacial institution that is carrying the loan. None of which are willing to do anything about it. Karmart says, because there are no codes coming up, to show there is actually a problem, there is nothing they can do. They also said they've tried to re-create the probelm but were unsuccessful. I would think that would be the case, since my car was not driven more than 4 miles in the 3 days they had it in their shop.